Not really sure. We bought it not too long ago. The person we bought it from did take care of it fairly well, oil and what not. But I am not sure if the trans was serviced properly or when.
It is just some thing that I noticed the last week or so.
I did give it a good tune up (plugs, rotor, cap, wires, air cleaner) recently and the TPS was going bad on it and replaced that.