2000 Chevy Impala Windshild Wiper Motor or computer problem

Last winter, when I had been driving my car in the rain, I cut it off with the wipers still on - which has been my habit of 35 years. This time, while the car was still parked, we got some snow. (I live in Richmond, Va - it doesn't happen very often any more.) So when I went to start the car the next time, the wipers were still up (i.E. Not in their parked position). The wipers still worked just fine except that now when you turned the off, the resting position of the wipers is vertical instead of horizontal. This is interesting because even in intermittent mode, the 'system' knew the resting position was horizontal. I had this fixed in April which cost me $260 including the labor. Now it has snowed again for the first time since it was fixed and it has happened all over again.

My mechanic says that I should have turned the wipers off to prevent burning out the motor. I don't disagree with that but I do have 2 arguements still. One is this has never happened to me before this year in 35 years of driving. I have numerous times had my wipers frozen to the windshield. I freed them but they were never permanently in vertical position at rest afterwards. I think this expectation is unrealistic. I polled several drivers and they all say they typically do the same thing - they just turn off the car. Secondly, the motor apparently isn't burned up since the wipers run perfectly. They just don't rest perfectly.

What do you think is wrong with them so I can get this fixed. I don't think it should break every time it snows.