Did you eat something salty? We had ham yesterday and I can barely get my usually loose rings on this morning!
Sometimes weight bearing exercise makes you retain water. Did you work out this weekend?
A pound is the equivalent of 3500 calories or approximately 70 pts. So a 2 lb gain would be 140 extra pts. That would be not impossible to do, but I would bet it is either water weight due to exercise, salt intake or sun spots

.
good luck. If you have been following the program, then you'll lose that excess
weight by your next weighin.