This problem can be fixed by replacing the mirror actuator in the passenger side mirror. I have included below a technical service bulletin that has information on this repair and the parts needed.
Bulletin No.: 02-08-64-008
Date: April, 2002
Subject:Uncommanded Movement of Outside Rearview Mirrors (Replace Mirror Actuator)
Models:2002 Chevrolet and GMC S/T Utility Models (TrailBlazer, Envoy)2002 Oldsmobile Bravadawith Memory Mirrors (RPO D25)
Some customers may comment that the outside rearview memory mirrors (RPO D25) may wander or may not go back to a previously set position. This condition may affect both mirrors or only the left or only the right mirror.
This condition may be caused by system interaction between the outside rearview mirror(s) and the Driver Door Module and/or the Passenger Door Module.
Replace the power mirror actuator(s) on the affected mirror(s) using the following procedure:
Caution : Approved safety glasses and gloves should be worn when performing this procedure to reduce the chance of personal injury.
Important : Under normal conditions, the electrochromic glass in the left outside rearview mirror would not be serviced as described in the Mirror Face Replacement procedure in the Service Manual (SI2000 Document ID # XXXXX). However, replacing the actuator requires the removal of the mirror glass assembly. The mirror glass should not break following the replacement procedure below but in the event the glass is broken or damaged, the RH glass, P/N 88937195 and/or the LH electrochromic glass, P/N 88494480 may be ordered separately. Replacement of the entire mirror assembly is not required.