We had something very similar happen with our girl. She was on a few different meds to treat her UTI, but throughout she would pee in her sleep, or sometimes on laps... just peeing without knowing she was doing it at all. Our doctor said it could be a few things, which we ruled out one by one: UTI (the sleep-peeing happened even after her other symptoms disappeared so we ruled that out), a conformation or bladder formation issue (ruled out by an ultrasound), or just that she's a puppy and will grow out of it. Seems to be the latter, as she is just over 17 weeks now and we haven't seen the issue for about a week. I'd check in with the vet to rule out the other issues, but it really may by something she grows out of quite quickly.