As others have said, it depends on the social contract. Personally, I lean more towards "The DM is right, even when he's wrong." But, that assumes the DM isn't on a power trip or a complete jerk (however you want to define "jerk").
Let me ask you this: Are you, in general, happy/comfortable with the way your DM handles the game? If so, you've got a good DM for the group. In this case, you've fallen victim to the fact that DMs are also human and prone to acting such. No one bats 1.000. If you come at him adversarially, you've reduced his ability to gracefully back away from that ruling and/or just do it differently next time. If it's really important, then you should discuss it. Either way, keep in mind that two wrongs don't make a right.
I've been gaming for just over 30 years, and about 75% of that has been as a GM. Because folks keep coming to me and asking me to run games, even when there are other GMs available, I assume I'm reasonably competent. I still screw up. Sometimes, I have streaks of bad rulings or evenings that just kinda suck. I also generally know when something's not right, even if I'm not quite sure what.
I've had players who would pull out various source books and confront me anytime they disagreed with something I said. Because part of the GM's role is to have hidden knowledge and lay plans that provide entertaining challenges for the players, there's an associated authority that must come with the territory. Heck, just to keep things moving, you sometimes need to have a final arbiter, which is why Gygax often used the term "referee". That dynamic is all part of the back and forth over rulings, whether or not any of the parties are consciously aware of it. Being confrontational about a bad ruling, especially in the heat of the moment, puts the GM in a spot where he isn't just defending one call, but his ability to function in the role he's been assigned by the group. Sometimes you make a call you know isn't perfect, but it's the best you can do, at the time, and the secret knowledge you have about the game world tells you that it really isn't worth derailing the game to come up with the "perfect" ruling.
That said, this only applies if the GM is generally good and/or is a beginner who is still working on his skills. If the GM is on a power trip, confronting him isn't really going to do anything other than give him an opportunity to flex his muscle, anyway, so it's still not the best approach. But, if he's generally adversarial, you might have a conversation about that, using this as a specific example. The GM has more impact/authority in a game than any other player, but it comes with just as much responsibility. In fact, I'd say it's the responsibility that begets the authority, not the other way around. If a GM is engaging in bullying or other inappropriate social behavior, then the group ultimately needs to decide whether to continue to allow that and/or how to encourage other behavior. I just really want to caution you to know the difference between a GM who is not taking his responsibility seriously and one who is inexperienced, having a bad day, or just plain tired.
My current players, much to they're credit, have learned how to question a ruling without being confrontational. They may say, "That doesn't sound quite right," or, "That's not playing out how I envisioned my character. Is there a way I should have built it to do X," or something like that. Sometimes I give the PC the benefit of the doubt, sometimes I don't, but the approach the players take gives me the opportunity to say, "Here's how I'm going to rule it, right now, to keep the game moving. I'll review it, between sessions, and we can talk about it." Sometimes, I change my mind -- I had a thread, here, a couple months ago to get input on sleeping/ambush rules. Sometimes, I decide it stands. I may or may not justify it much. I also don't retcon the original session, but that's one of the reasons I tend to favor the PCs if I'm in doubt. The other answer that I occasionally give during a session is, "You know, your character doesn't think that's right, either. There may be something else going on that could be handled in-game."
