Sounds to me like your cover has a static charge.
I never, ever use the cover. I've tried it both ways and found no difference. "Draft" doesn't begin to describe the airflow it takes to effect the scale, in my tests. Hurricane would be a better word.
Still happily answering to the call-sign Peetza.
You do not HAVE a soul. You ARE a soul. You HAVE a body.
He is no fool who gives what he can not keep to gain what he can not lose.
-Jim Eliott, paraphrasing Philip Henry.