Yes, I noticed a change and I guess they have been fiddling with the search engine for quite a while now. In April I uploaded around 80 new pics and barely made the payout in what should have been a record month. My port is not that big - around 1.100 pics - but I think it's big enough to notice changes in the search engine.
In May I have 5 days with low single digit downloads - some of them perfectly normal weekdays, like Wednesday or Thursday this week, again with 20 additional pics online. If something sells, it tends to be older files from my port...