Suddenly had extra ads, popups, and new search results show up and your virus and spyware scanner reports everything as a-ok? It might be to do with the report from Ars on Adware vendors buying Chrome Extensions and updating them with spyware. Because Chrome extensions update silently, and are out of the scope of spyware and virus scanners, it’s a great new vector to use for scammers and advertisers. Other things:
Something to be aware of. If google was smart they’d either add in some sort of spyware checking, or add a notification to the user on either extension ownership change, or a more obvious changelog.