I feel ya. I just did the same thing over the weekend. I knew it was going to happen, because I was going to a baseball and soccer game with people who drink, and I'm terrible at just saying no. Because we were in a larger city we took advantage of the 'western' food and I pigged out. Not like I used to, but definitely way over even maintenance calories. It was only 2 days, but it was enough for me to gain 2 pounds.
It sucks knowing that it took 2 weeks to lose that, but yet I can gain it back in 2 days. I was crushed when I stepped on the scale this morning but it was what I needed to get right back on plan.