You heard right, WildMan. When you brake in reverse, it does a slight adjustment.
And Buick, the only way to check the drums is pull 'em, unfortunately. Older cars had "peep holes" for checking the shoues, but the drum you want to check to see how worn down they are. And don't be suprised if they take some work to come off. They tend to stick after a while.
Definitely want to consult a manual of sorts to verify the correct procedure. Drum brakes are a PITA.