It really doesn't matter either way in this situation anyway. Even if he's not omniscient, he might still know from any of the myriad ways gods learn stuff. Heck, a raven might have found itself thinking it was courting with another raven, only to discover she was flirting with an the imp. I'll leave the details to your imagination, although my whole reason for this post is to plant that seed in your brain. Anyway, news of this strange event could reach Odin's ears, and lead him to discover the gullible paladin's hapless circumstance.
What really matters is if Odin cares. And then even if he cares, what's he gonna do about it? As a DM, I see some fun opportunities there as a DM.
(And on a side note, I can state unequivocally that Odin's not omniscient. I've watched the Xena episodes where he appears.)