2000 Alero sealed trans...service?

I have a 2000 Olds Alero, 3.4L V6 with an automatic sealed transmission. There’s no dipstick. Supposedly, it should never need service, but I have my doubts.



It has 114k on it, and the trans seems to be just fine, except when I start up in the morning.



My driveway is on a slight angle, and if I start the car and try to stick it in reverse right away, it does so with a loud noise and a jerk. If I let it warm up for about 20-30 seconds, it’s fine.



Should I be concerned? Is there anything I should do? Otherwise, it shifts just fine, just like when it was new. I just feel like at this many miles, there should have been SOME kind of maintenance.