Blood sugar post op

I had my vsg on 11-29-11, even at my heaviest wt. my blood sugar has always been good. Since my surgery my HA1C has been up a little, had lab done last week and it's still up 5.3 I don't understand this why the jump I've lost 50 lbs not eating near the carbs or sugar I was pre-op.
My other labs are all great btw, my potassium is back up, lipids are coming down nicely w/o meds, still off b/p meds and it's stable, iron is great so a lot of things are GREAT! I'm confused my doc says she hopes it's just a temp. adjustment for my body but we will keep an eye on it.
Just wondering if anyone else has had this problem who weren't diabetic pre surgery.