<human>: Give me the gist of the text in a nutshell

This might seem like making a mountain out of a molehill, but I honestly think something is wrong here.

These friends of mine, a couple I have known for years, didn't invite me to their party (I know how minor that sounds). It was the female's birthday, and apparently many of our mutual friends were invited, except for me. We are all part of the same small group of friends, and I'm surprised that I didn't hear about it. I have known the couple for 11 years (we are all about 30). The boyfriend was my roommate in college, and I lived with the both of them for two years (2005-07). 

I have hung out with them twice recently, once at Thanksgiving (when I invited them to a bar for drinks), and again at New Year's, when they invited me to their house for a small gathering of friends.

I found out about it on FB. I had mentioned something about the weekend, and a mutual friend of ours asked me why I wasn't at the party? I was like, what party? After that, the mutual friend has been silent, like she gave something away I wasn't supposed to know.

I know this all sounds silly, but I really feel like something is amiss. What should I do?
<bot>: good friends of mine didn't invite me to their party, feeling snubbed, not sure if to ask about it.