Just because no one knows you like Pokemon, does not negate you from being a target. It would be someone you wouldn't know in the case of a virus catching your password, and at least it seemed to be a harmless prank. Viruses don't pick the victim, especially on public computers. They take all who come.

Knowing someone in real life does not make you safe from being hacked. In fact, it makes it easier for them due to the fact they can remain anonymous. Your friend may have done a prank, and you should ask them if you can.

EDIT: Do what Sarah suggested, but do a virus scan first.