- Take down the offending images.
- The Statute of Limitations is 3 years from the time Getty discovers the mis-use. If their first letter was 2.5 years ago, you only have 6 months left. If you have server logs, you may be able to find when picscout crawled your page which would be proof that Getty may have known of the issue more than 2.5 years ago.
It is my belief that over the years Getty has changed their policy with respect to images. There are lots of years here between the time you got the image and the time they accused you of misuse. In that time, Getty has gone public, then, private, at least once, and possibly more. How they distributed images in 2004 is different than how they do so today. They have removed access to copies of certain web pages prior to 2009 on the wayback machine. My thought is, if I were in your shoes, I would wait out the SOL. If Getty should file anything, I would give them hell, but I don't expect they will as, they must know the images that are frequent offenders and must suspect that they were complicit in seeding the market with those images.
Good luck. Their is lots of good info on this site to educate yourself about Getty. Take advantage of it and don't worry to much unless they actually do something.