Never had a problem with my Gra-Lab but I still pull a flap of black duvetyne down over the face when I have film out in the darkroom.

I know that, for short periods of time, it won't make a difference unless you have super high-speed film but, for the ease and simplicity of covering the clock, it's good insurance.

Yes, like others, I have forgotten to cover the clock and have handled film with no ill effects.

My clock is nearly ten feet away from the bench where I handle film and three or four feet away from where I develop prints. Have not had a problem, yet.