[Funkduder]

Hmmm...interesting... And I don't suppose you'd be worried if one of those texts resolved the issue...let's see.....................

The simple way to deal with it is to ask, but whose to say that they would tell, and if they did if they would tell truth.

As for speculating, if it turns out that your friend's mother knows who you are, it could be that she is either worried about you being with him, friend or closer otherwise, or it could be that she doesn't know you and is equally scared. It wouldn't be surprising if his mother's worries were completely irrational and poorly based.
Then there's the possibility that his 16 year old mind has other things on his mind. I wouldn't know, but it could explain a lot.
Being 17, I know it's equally possible that he was thinking the way your aunt was, before she told you. It could be possible that his goals and motives triggered your aunt's speculation. I don't know your friend.

Either way, if it turns out that you can't know anymore for whatever reason, it could be that someone appropriately wants you not to know. In that case, it would be best to ignore the feeling and move on.