Sometimes I think people will detect something different about you, but not really notice what it is, so no comment is made.
I know to YOU the beard/mustache shaving was a big deal, but maybe others couldn't put their finger on exactly what had changed. I say this because I've done that very same thing to my brother. He has had a goatee for a number of years, but there have been easily 3 times in the last 4 years where he shaved the goatee and I "didn't notice". It wasn't that I didn't notice ANY change in his look, but my mind didn't register that it was the facial hair. When he finally told me he shaved his goat, it was like his feelings were hurt a little as well. He just couldn't understand how I didn't notice exactly what had changed.
Maybe it's a function of the busy world we live in...we are all so concerned with the tasks we have on our plate and what's going on in OUR OWN WORLD, we forget to notice the changes in others.
Has anyone asked if you got a hair cut or lost weight or anything? Sometimes that will be a manifestation of their noticing a change but not knowing exactly what has changed.
Either way, don't let it bother you...after all, regardless of what issues you have swimming in your head, maybe the others have equivalent or bigger things to deal with. I think that's why we gravitate towards people who are empathetic and want to sit down for 15 minutes and talk about what's going on in OUR world.