I noticed the same thing. I am also on GoDaddy.
One thing I found was my header.php had been modified with a hidden div that pointed to “Faxless Check Cashing Online”
I host 4 WordPress sites on my GoDaddy account.
The wpsystemadmin account appeared on 2 of the 4 sites, and was only Administrator on one site (the same on with the modified header)
