Absolutely have her checked by a vet. UTI is the most likely culprit - and if she doesn't have that, then at least it can be ruled out. Other causes could be another disease, such as diabetes, and renal disease among others. Your vet will probably ask if she's peeing more frequently, and if the volume is more or less than normal.

I'll check back on this thread, to see if she does have a UTI - if so, the solution is simple. If not, I've got lots of ideas.