Different behavior

Nicki has always been very good about going outside to do her business, but lately she has been asking to go out and once outside she just stands there. She then comes back in and then asks to go ouotside again. At which point she just stands there looking at us. She started doing this a month or so, and now woke me up at 5:00 this morning to go through the same routine.

Has anyone else experienced this phenomenon? Is this something physical, such as some sort of infection, or is she trying to tell me something - like, "stop giving the cats all the attention and play with me!!" Trust me, she is one loved dog and gets PLENTY of attention, so what could be wrong?