OP, I'm maintaining now too, not 7 years worth, true, but still maintaining. And I sometimes eat pizza and sometimes have a glass of wine and sometimes say "I've had a bad day so I want a frosty, heck with the consequences". Then I get up the net day and get back in the groove. I think what you did yesterday was just fine.

Really, when I reread your post it didn't look like you went all crazy, either. Just that you had some pizza and wine and took a day off from exercise. 300 extra calories. Which equates to 0.085 pounds, if you don't work it off in the backbend class. Not that you planned to make it a long term habit, and you already had the next day scheduled. Sheesh.
I'm sorry, I know that you know all of that. I just felt like saying it.
Good luck honey. Don't let the scale, or anything else, get you down.