There's a lot of things this could be. First of all have you changed your diet? Then there are at least 3 things that all have similar symptoms including more frequency, they are:
pouchitis
cuffitis
c-diff infections.

The only way to tell is to go see your doctor. You should be due for your first pouch scope so if I were you I'd schedule that and tell your doctor your frequency has been increasing so they will take more biopsies. The scopes are very easy, compared to colonoscopies etc.

Good Luck!

TE Marie is right. Pouchitis is the first thing that comes to mind. I've had it a few times over the 15 yrs I've had my pouch; most of it occurring in the 1st 5 yrs. Only your doctor can tell for sure what's going on by scoping your pouch. Antibiotics usually take care of it quickly! Of course some dietary changes may need to be discussed with the Dr. as well.