Yeah, that happened to me too. Don't worry too much. Drink lots of water and check that you are eating enough veg. You will get back on track soon enough. :gen126:
I wouldnt worry about it, I put on 2lbs last week and I was super strict. Could be a number of different things, but with a 6lbs loss the week before, it might just be your body settling in to your new way of eating.