Looks like it.
Is this behaviour an artefact of the coin itself or something else?
I don't know, maybe the zero-bounty-blocks confuse the pool software? My p2pool runs without problems so far. I lowered the fee to 0.0 % to offer new users a stable pool to mine on as long as the other pools are this unstable.
Switched to your pool and already got my first payout. P2Pool rocks.