Well you have an OBD-II car so you could take it to an auto parts store or mechanic and have the system scanned for trouble codes. That would give you an idea of if the car believes theirs a fault in the system.
I'm an advocate of changing the trannsmission fluid. Everyone gets confused by BMW's statement of "lifetime fluid". However that statement is meant to be the lifetime of the trannsmission. So if the tranny lasts 100,00 kim then that was its lifetime. However, ALL synthetic fluids break down over time. And because of this they should be changed. Some people report better shifts after having done it so their can be a benifit.
PelicanParts.com has a transmission filter and gasket kit available. All you need is the Trannsmission fluid. For that most people recommend Redline fluid.