Sub-concussive blows can cause damage but it is due to an accumulation of hundreds and thousands of sub-concussive impacts. This would be common to a American football lineman who suffers 600 to 1000 subconcussive impacts in a 4 month season.

A single sub-concussive impact has not risk of damage. Becoming anxious and remaining anxious has more long term risk than a single sub-concussive impact.

What are you anxious about ? Even if you suffered some very minor brain damage, the brain is very resilient.

Do you ever get drunk ? Some say getting drunk is like suffering a minor concussion.