Resolved - I phoned Apple on a totally different issue and was on the phone for about 2 hrs and after that was resolved, he took care of this as well as it kept cropping up while he was trouble shooting.
Bal I hope you are running the Real Time Protection option in Malware Bytes. It should block this kind of item from showing up. I have no idea where this would come from but I would think somehow you got infected from perhaps an email or website button selection you perhaps should not have clicked?
Did the Apple Support person mention anything about what this was from or how he "resolved it"?