A very similiar thing happened to too. I got close to my goal weight after 2 years of dieting. I somehow got it into my head "That's grand, I'm fairly slim now, I can relax a bit and eat what I want".
Obviously the weight crept back on. The only thing to do really is re-commit to healthy eating. Don't let a wobble throw you off completely.
Best of luck getting back on track. And remember, you can do it. You know you can, you did it before. So keep at it, and at least this time round you will have learned the lesson about how easily the weight can return.
At least you realise and now you can lose that little bit again right? And just think to yourself its nowhere near as much as you had to lose in the first place
Try and use positive thoughts 'oh, Ive slacked a bit, not been as great as I could of been - but now Im back on it again and Ive learned from my mistake' Hehe