My other account logged in but really not?

I logged in on this account this morning to find that my sons account is online. His toon showed up in guild box and was online. Now my son is a kid and we play next to each other so immediately I thought I got hacked> I have an authenticator and follow all protocols not to get hacked.

Now, i then log onto his account thinking I will boot the hacker off them log onto Bnet and fix what I have to.

The problem is I think that the his character Portz of Turalyon was simply a ghost and I wasn't hacked or possibly being hacked.

So is it possible that a Blue can confirm this in some way shape or form.

1) Was my sons account on this morning around 5 or 530?
I was on earlier lvling his hunter until about 4 AM but after that his account should have been logged off and his mage named Portz should never have been on. Is it possibly a bug from the patch?

2) Was there any attempt on my Bnet account for password change or anything this morning? I logged in before 6 and after 530 when I saw his account was on.

Any help would be appreciated cuz now I'm scared. lol thank you