Yes! I'm the queen of throwing the arm out reflexively on a hard brake to stop my bag from flying. Was driving to lunch with a friend in the passenger seat not too long ago and did it to him! He said "Nobody has done that to me since my mom when I was like 6 years old". I saved him!! LOL
I do that all of the time to my husband (for the same reason you describe--I get so used to doing it for a bag)! lol.

