David, you are right about the contamination. In fact, I'll have the washer on trickling down until I get the third or forth print in there, then I'll turn it up and watch the clock. I haven't seen any discoloration in my prints yet, but I've been using this washer for a few months. I don't think that they will, though.
Another thing you might want to do (which I don't do all the time), is rotate the prints in the washer after a while. That is take the top print and move to the bottom, and take the bottom and move to the top, etc.
Good luck,
André