To expand on what [MENTION=6776133]Bawylie[/MENTION] said, my advice is to simply gloss over it and give the PC's more information than they actually ask for. The dwarf sings like a canary.
Think about it this way. One of the biggest challenges for a DM is to get information into the hands of the players. Either setting information or plot information, doesn't really matter. How do you get the information from your head into their hands? Well, they just handed you a gift wrapped golden opportunity. All those cool ideas that your have for your setting? Well, hand them over now.
I suggest that you take a few minutes and type up (or write up) a page of information in bullet form. Twenty things you learn from the dwarf or something like that. Depending on where you want to nudge your players, tailor the information in such a way that it allows them to make informed choices. If they are interrogating the dwarf about some stronghold or camp or something like that, give the players lots of information about that - total numbers of people living there, what are they armed with, maybe a tidbit or two about different NPC's (Toegrap likes sweets, offer him some candy and he'll be your friend) things like that.
Now, for a twist, add in maybe two or three items that are deliberately misleading or outright lies. Maybe Toegrap hates sweets in fact. Maybe there are more (or less) defenders in the stronghold - the number the players get is off by 10-20%. Don't do this with every piece of information. Make most of it true, which makes the false stuff stand out nicely. Note, if the players go the magic route (Zone of Truth or something like that) then don't negate that - they know that X is a lie and maybe they can get the truth out of the dwarf.
DO NOT STONEWALL. This is the biggest mistake I see DM's make in these situations. They don't want to give out too much information for fear of making things "too easy". It's never "too easy". Having information lets the players make informed choices which makes them actually think (and get more immersed) in the scenario. Coming to a T intersection in the dungeon is not a real choice - it's a coin flip. Coming to a T intersection where you know left leads you to the the armoury and right leads you to the Captain's chambers is an interesting choice.
This is not a challenge, it's an opportunity. You can expostulate to your heart's content. Do so. Your players are telling you that they want more information. Give it to them.