Winder magnitizes my watch.

[dricig]

Just wondering if anyone has ever heard of a watch winder magnetizing a watch.
My 16750 always runs great at +3 sec/day. I noticed last month that it was gaining 15 sec/day so I demagnetized it and it returned to +3.
After some experimenting I found that after a day on my winder the watch gets magnetized again and a demagnetizing returns it to normal.
Of course I am going to dump this winder (Its an inexpensive AC single winder I received as a gift) but I was just curious as to anyone hearing of this before.

thanks