Welcome to the forums!
First I wanna say that thanks for posting, I haven't seen a question like this ever but it's a very good one.
From what I can tell, this might be because of some hormones but it can also be from stress or worrying. The hormones might be affecting your judgement and might swing your moods to over react a little bit.
You could maybe tone it down a bit (if you wear short shorts all the time), but there isn't much to worry about because not all fathers do this and you feel calm with your father. You could also tell yourself or reassure yourself.
Still, the best
thing you can do is talk to your own dad about it to get reassureance. I'm sure he'll understand if he knows enough of the story. Then he can give you advice from there.