Tycho, I'm certain I haven't done proportional -> pps switch during shown blocks, furthermore that problematic block was in the middle of the night while I was sleeping and I don't have any software for automatic management of my workers. Too bad I don't have access to some log so I can prove it, my miners haven't reported anything strange about rejected blocks or something, but maybe you may check it out in pool logs and pass me info via PM or even better make more info accessible on the site.

0.4 bt cents is not much of difference, but I'm more interested in the true reason why that happened and to help you investigate the case so it won't repeat. I'm developer myself and I don't like when things don't work as expected