+5 Teamwork?

I just got +5 teamwork after a game. Now I was playing with friends and I appreciate the +4 teamwork, but +5 would imply that I voted for myself, and some how gave myself positive feedback. I did go legendary, but I wouldn't think that would give me a bonus +1, unless RIot is testing something new we don't know about.

Would this be a bug? Anyone else seen this before?

Sorry I didn't take a screenshot of the +5, but it was there. I'm on a Mac if that matters.