My wife and I have been together a long time. She is blunt with me and has been since the beginning of our relationship when she told me, "You don't have to read between the lines with me. Just read the damn lines." (I paraphrase). It can sting, but I wouldn't have it any other way.
We all have an ego. I sure as hell do. If I had to guess, your husband had been dropping hints for weeks that you didn't pick up on. Then he hid your grandma outfit because you blithely ignored his ever more blunt hints.
I'm also guessing he loves you and finds you attractive, otherwise he wouldn't care. I suspect he was thinking, "WTF happened to my girl? Now we're retired so she's going to schlub around with me looking like a grandma caricature for the rest of our lives?" He hit a breaking point.
A guy's 2 cents