Transmission noticeably downshifts when stopping
 

The truck is a '92 K5
I believe the tranny is a 4L60

When I come to a stop I can noticeably feel the transmission shifting from 3rd to 2nd, and then 2nd to first...like some kind of engine brake. This is the first auto transmission equipped truck that I've owned since about 1990, so I do not recognise(or LIKE) this function. I'm a

Is it a malfunction? Can it be repaired/bypassed?
Hook me up with some knowledge!