Just wondering if this is a normal, nuisance, or serious problem.

On OCCASION, if I insert my key, glow, and try to start my car, if it fails to start I cannot move the key to the start position again. I have to turn my key to off, remove key and start over again. Sometimes if I just turn the key to off, reglow, I can move it to the start position with no issues.

Thanks!

'78 240D 4spd.