co workers

So today is my birthday & I went to work. I've been working in the same place for 3 years now & if any of you don't know offices are big on finding any excuse to have cake. My department has a calendar with everyone's birthday on it & today my birthday went unacknowledged. I can understand if people don't want to spend the money but you would think that they would at least tell me "Happy Birthday." Maybe it doesn't really matter but I always tell them "Happy Birthday" when it's their birthday & participate in whatever celebrations. It just makes me think I must not be very well liked & maybe I'm more unpleasant than I thought.