I thought I'd let you all know that I didn't even have to say anything to BiL.
When I saw him yesterday, he said "Yeah, I don't know when I'll pop the question though. I thought about doing it the Virginia weekend, but I don't think I'm going to now, because of the wedding."
Such a smart guy!
My husband thinks BiL said something to their mom, and she likely told him to not do it that weekend.