I can confirm this in my Google Webmaster Tools as well. It seems that the only place this URL exists is in a bit of Javascript code that vBSEO adds to the end of each page. Not sure why GoogleBot is crawling the Javascript but I will see if there's a way to fix these URLs.
As a side note, I remember something similar happening with non-wiki URLs in the past, but it seems vBSEO has fixed this because I haven't had problems with, for example, online.php for several months now.