Never happened once in all my trips back to Texas. I suspect there were too many people like my Dad that would have swung first, and worried about the consequences later. Somebody wants to spit, they might as well spit some blood.
Most of us Dads in Texas are still that way...
Our youngest son fought 2 1/2 long years in Iraq and I wouldn't stand for that behavior then nor will I today. During VN, I had a friend that rearranged a hippie's nose for making a smart remark when he came back.
I always traveled in uniform coming from and going on leave, we have given too much ground to these traitors, time to take our country back.