OP's story reminded me of a situation I was in several years ago when I was teaching at a small private school (about 20 teachers). I walked into the office to make copies one day and found a party invitation sitting in the copier -- it was for a housewarming party for the math teacher. Because it was brightly colored I couldn't help but notice that there was a copy of the invitation in several teachers' mailboxes, but I didn't receive one. I figured that either she hadn't finished distributing the invitations or I wasn't invited; since I wasn't particularly close to the math teacher I didn't care much if I wasn't invited, and wouldn't have given it a second thought (other than a second of annoyance about having left the invitation in the copier for anyone to see if she didn't plan on inviting everyone).
But then a few days later, at lunch, with several other teachers present, the math teacher said, "I don't understand why so few of you have RSVPed to my party this weekend!"
The computer teacher said, "I didn't RSVP because I didn't receive an invitation." and I piped up and said, "Me either." -- thinking that, if she was talking about it in front of us, my lack of invitation had been an oversight.
Not so. The math teacher just said, "Oh, that's because I didn't invite you."
I said, "Oh, okay," but later on checked in with the computer teacher -- "That was kind of weird, right? If we weren't invited, why was she talking about it in front of us?" The infinitely older and wiser computer teacher agreed that the math teacher should have been more discreet about the details of her party.
Unfortunately, I wasn't paying much attention to who else might have heard me say that, because later that day I was confronted by the math teacher, "I heard you were upset that you weren't invited to my party. I can't fit everybody in my house, I couldn't possibly invite everyone."
I kind of stuttered and stammered, "No, that's fine, I understand, I wasn't upset that I wasn't invited, just confused that you were talking about it with people who weren't invited."
And she just continued with, "You should know I can't fit everybody into my house, you shouldn't take it personally that I didn't invite you." I don't think she ever really understood that it wasn't the lack of invitation that irritated me, but her open discussion about it in front of me.