87 190 Dt

I recently had the transmission rebuilt and the shop is telling me that I need to drive the car 500-1000 miles and then they can make any adjustments.

The problem that I am having is the transmission after completely warm doesn't seem to shift back into first until you press the accelerator which makes the car jerk taking off. The rebuilder says that there is a valve sticking and it needs to wear in.

In my opinion, after spending this much money it should be perfect from the beginning. Do I have something to worry about or should I give it time? I already have the 500 miles on it and it has only improved somewhat.

Thanks