(I have gotten some
very strange looks lately when someone asks me about baby signing and it comes up that we've done the ABC Signing Time DVD. I get the feeling that I'm coming off as a pushy and extremely delusional mom... but she memorized all the other DVDs and is now signing some of her ABCs. Should I just keep quiet? Probably.

lol! That one brought up memories. I recall being perplexed as to why people would want to teach 9 - 12 month old babies sign language in order to communicate with them b/c dds were both speaking and speaking well enough to hold simple conversations and get their points across by that age. (9-12 months seems to be an age where there are baby signing classes available locally to me.)
I guess that I straddle the line btwn you and your dh. I don't lie or totally downplay dds, but I generally didn't respond to things like the sign language stuff w/ "why would I do that, dd can speak?" There are people with whom I am completely open, but they are few and far btwn. I think that, especially as they get older (dd13 is a high schooler now), and you have a HG+ child, it is so obvious that the child is different and parents have gotten beyond the belief that if they just worked with their kids, they too would know their ABCs in sign language.
I don't pretend that dd13 isn't in high school or isn't taking the classes she is or doing the extracurriculars she is, but I also don't randomly walk up to people or co-workers and discuss it either unless "how are the kids liking their new schools?" is a topic that someone else brings up or I need to vent about something that is going poorly for dds.