I actually made it more common when I released the Giselle thrift rat set. :) and I adjust the rates for different random events when we feel the need to. Generally around the time we do a new set, we make the random even more common for a while.

I've increased the odds for them again a bit, but they are fighting with a lot of other REs now! Keeping an eye on them for the next week or so to see if I need to increase them again :)