soft stool sticking to fur

Question
I have a female mini rex rabbit who is almost a year old. About 2 days ago I noticed that she had alot of soft stool that appeared to be stuck to her fur around her backside. One day there was nothing there and then the next it was there. It's gone now but I'm concerned as I don't know where it came from. Her cage is clean and we keep her litter pan clean. I'm not sure if it's the type of rabbit pellets that I have her on or what else it could be. Any advice or ideas would be helpful. I'm thinking about taking her to the vet to make sure she's ok and as nothing was said at her last vet visit. Thank you.

Answer
Does she get all the fresh grass and or timothy hay she wants?  Rabbits lacking in enough fibre in their diet often get runny stools. If there is plenty of hay and she is eating it, she might have an illness. Stress (such as a move, changing her diet, etc.) can also cause such things. If she is not getting hay, that is likely the problem. If she is, taking her to a good rabbit vet would be a good idea to make sure it is not a disease.