the 99 SVT I currently have, the e-barke sticks when it sits over night, and my other, 2000 SVT did it too from day one with 48 miles on it the back brake would stick. So I'd say that the e-brake sticking and making the pop sound when you start moving is perfectly normal.
The reason they are telling you your rear brakes are worn is becasue there is nothing physically wrong with the car. If they come to you and say "we found nothing wrong," they're afraid you will figure they think you are a dummy who doesn't know a brake rotor from a hot rock.
And 3mm, thats almost nothing, I'll bet that when they tell you the pads are 3mm thick, they are refering to the pad having 3mm more material than the minimum ammount specified in the service manual. I'm sure they will last until the fall. Besides, I recently changed the pads on my SVT, and it did nothing to stop the sticking e-brake.
When the brake sticks like it does for us, there is nothing wrong with the actuation system, it is simply the pad seizing to the rotor
