Make that three invalid blocks in a row.
I would guess this is a sign of work being done in the background. I believe these blocks are not invalid but marked as such on the pool level (so they do not interfere with rewards), so the operator has some headroom to fix things. We can confirm this once blockchain.info gets back up again.
Bockchain.info is back. My assumption was wrong, these blocks seem to be orphaned indeed. All 3.