so true, kelly0523... that chill you describe happens over the simplest things, too - innocuous questions like "what grade is she in?" when DD5 drops some crazy vocabulary or randomly calculates something in front of them. it used to be so difficult to say "Pre-K" to that... it was a total conversation killer and people would make the craziest (false) assumptions about us. that we had a tutor for her, or a truckload of flashcards, or some kind of creepy Clockwork Orange setup... which is natural, i guess, but it was pretty hard to make friends with other parents when DD was in school when they came loaded with so many preconceptions.
mercifully, now that we're homeschooling what amounts to a triple+ grade skip, it's a lot simpler. we just say, "oh, we're homeschooling so we skip around a lot." it's the exact truth - and delightfully non-specific. people then usually follow up with "oh, wow - what's that like?", and they completely forget to ask more about the actual grade! whee