Heading a soccer ball would often be considered a sub-concussive impact but getting a shoulder shove would not.

BUT, sub-concussive impacts are not a cause of injury individually. It takes hundreds in a short period of time for the cumulative effect to make a difference. The common sub-concussive issue is a football player sustaining 800 or more in a 3 or 4 month season. This is often smacking helmets at the line of scrimmage or repeated hard tackles smacking the helmet on the ground. Or, a soccer player sustaining 10 to 20 headers during each practice for an entire season.

Unless you buddy smacked you in the head, that would not be any kind of head impact.