Any "surprise" can be fearful. No you're not afraid of the actual hit but you sound like me and bee stings; I have been stung by a bee too many times as a child but that didn't mean I didn't anxiously look for bees when I was barefoot :-)

I remember once when a bee got in my car while I was driving and I had to "teach" myself to relax and drive rather than get upset about the bee. It did eventually sting me on the neck. It's a built-in thing, anticipating a punch/injury and "getting ready." For all your body knows, it could be a "knockout" punch or break a bone, etc. It would rather you avoided the punch, not "look forward to" it