S.L.
I agree with Lisa. If she is teething that my have caused her to temporary regress. Sometimes when children are on the verge of a major milestone, you will see a temporary lapse in another one, especially if they just met it; not to mention if she is already cranky due to teething, she might be getting frustated easier and giving up quicker than she would when she is her normal, non-teething, happy self. If you are really worried though, I would call your ped. That is what they are there for and they can probably put your mind at ease better than anyone.
S.