We'll be married 33 next January...together almost 40 and my H forgets....dates have never meant much to him. Just mentioned yesterday that my Mom's 84th is coming up in a few weeks and we should do something and he had no idea what date it is.....after almost forty years celebrating it.
As to Dday my H doesn't remember that either, although we do something special around that time because I plan it and I bring Dday up. He always responds with apologies and agreement we are doing well considering what he did and we talk.
I bring these kind of concerns up to H since DDay....I hate stewing the thoughts about why he didn't say something or trying to read his mind to figure out what he's thinking. It works better to ask him and then see how he answers it.... how he responds is more important than if he remembers the date, but that's what works for me.
I think if this bothers you, it bothers you and you're not overreacting.... maybe you just need to bring it up and talk with him about it.