I think the main reason people are gaining is that like any fad/crash diet, they aren't losing in a healthy, sustainable way. Once they lose the weight, they go back to their "normal" way of eating.
I would suspect you might gain some initially but I'm sure your body will adjust. I'd recommend adding in strength training to your exercises as well because I would think you lost some muscle if you were following the very restricted calorie diet.
Good luck on your continued (healthy) weight loss.