I remember the time I left my phone in a car service, in New York of all places...got it back too, talk about great customer service. Turns out leaving your cell in a cab, car or uber is pretty common. Uber has also kept track of some strange items riders have forgotten in ubers....
Check out some of the 'most unique forgotten items' from Uber's Lost and Found Index.
Valuable Nordic walking poles
Engagement ring (it was a SIGN MAN!)
Hot Cheetos (I'd ask a driver to turn around for these too)
Back massage device (heh heh heh.)
Harry Potter glasses