A co-worker of mine has her birthday today, and some of the people from work are taking her out for happy hour. They have been talking about it today in the office in front of everyone, but not all of us were invited. We are a small office of 13, and about 8 people are going to this happy hour. I am the office manager, and I casually asked if this was an open invite and if more of us could attend to help celebrate, and they awkwardly dodged the question and said it was just supposed to be intimate and small. I don't have a problem with people not inviting everyone, but I do think it's rude that they are discussing it all over the office in public and they aren't including other people, especially when we are such a small office. I want to say something because I think this is creating an uncomfortable situation for the handful of us not invited, but I have no idea what to say. Any ideas?