MJ use to do this. when she would drop off to sleep i would change her nappy, which would wake her and then she would feed some more.
This seemed to help.

FWIW, MJ dropped her night feeds at about 8 weeks and then at 6 mths she decided that she needed them again and she is having 1, but usually 2 feeds overnight.

I would tend to agree with the others that it is a growth spurt thing.