I hear it's normal.
Also a banana counts as 2 fruit servings, that's a lot of carbs in one food item.
I had my RNY a week after you, I have also lot 80 pounds. The last few months have been a concern to me. 4 months ago, i lost 14 pounds, 3 months ago I lost 15, 2 months ago i lost 7, and this month? I'm fighting 3 pounds, i lose it, i gain it. I'm told not to stress over it. But it is distressing.
I eat low carb, and log all my foods, i even weigh them for the most part. Do you take your measurements? You should, it might tell you something that the scale is not.
Best of luck
7/18/10: 211lbs, 10/16/10: 174 lbs, 1/21/11: 146 lbs, 4/20/11: 131 lbs. Insulin FREE since 7/2010, "normal" BMI since 12/2010. I'm 31, 5'5", happily married, with a fabulous 3 year old boy, and hope to add to our family in the near future