I actually dropped may radio and the first thing I noticed was that my new 800 mHZ RS antennae was bent. You asked a good question and I wonder if I damaged my antennae by bending it. Lets see what others say.
My rubber duck is bent and in therapy for post traumatic stress after losing a fight with a ceramic flamingo. Until it recovers the flamingo's metal legs must serve as an antenna, a bit inconvenient for the flamingo but the ankle bracelet the judge ordered wouldn't fit.
I wouldn't worry so much about the performance of the antenna...I would be more concerned with the stress you are putting on the BNC connector. You should take it off of your belt before getting in the car.