Hey, mine was doing that too. On the passenger side. I parked the van
and was going through some paperwork for about 30 mins and when I pulled
away it started squeaking the way you described. What I noticed on mine
was it wasn't very consistent with the movement of the van. If the van
was hardly moving it would squeak just as bad. Went away after a day and
hasn't returned. 

Erik
87' Syncro Westy Camper