The same thing has happened to my girls (ages 4 and 6) a couple times over the last few years.
Sometimes, I think it's growth spurt-related. They seem to sleep a lot more deeply during a growth spurt, so they don't wake up when they have that urge to use the bathroom.
Other times, I realize that we've gotten busy with other things, and they're not drinking enough early in the day, so they aren't using the bathroom as much during the day. Then, they'd drink more in the evening and have to pee at night. When I upped their fluid intake in the morning and at lunch, their bodies adjusted, and they didn't have to go at night so much anymore.
One more thought -- has your daughter's sleep schedule changed? Did she drop a nap? Is she waking earlier in the morning? Has she been really busy with other activities these past couple weeks that have messed with her sleep? When kids are overtired, they often sleep more deeply, too, and don't wake at night to use the bathroom. Sometimes, one of my girls will have an accident a day or two after a vacation or something when they haven't slept on their normal schedule.
Hopefully, something there will help you. If it doesn't pass soon, it may be something medical, so it couldn't hurt to talk to her doctor.