norton internet security 2011/using windows 7 os

First off I'd like to thank the people behind this software, it has worked flawlessly and I continue to be pleased with it. (very well done!)

 

Question: Yesterday it removed a trojan flash10i.ocx in the sysWoW64 folder (trojan adclicker). How does one acquire such a gem? I did not use the adobe flash that day, and I had understood that this third party software had fixed their vunerabilities which I had downloaded/updated a few weeks ago?