On Oct 10, 11:43 pm, wrote:
Is it normal to have some air coming in from the fan into the
bathroom. I have a screen at the end of the exhaust pipe and there is
a flapper damper at the fan itself, factory installed. I cant really
use a sophet vent because it restricts the air flow and causes a
whistling sound when running. There was still air coming in that way
too, but not as much. Had to be windier. Thanks!

I think I can assume this condition is when not running. ; )
Cooler air will give you a draft (heavier air).