Yep, that's the slot. Sounds like the wood went on downstream. You would have seen it as it was stuck (loosely) on the rock immediately upstream of that slot on river left. It was stuck at a 45 degree angle, downstream towards river right and it was blocking most of the entrance to that slot. You might have dodged it if you were coming directly at the center boulder but you would have seen it for sure.
As I mentioned it was wagging, or waving, or dancing or something along those lines, but it sure wasn't friendly looking. It was stuffed up against the rocks but it was getting pushed around by the water quite forcefully.
I'd guess it was about 10 - 12 feet long and around 1+ foot in diameter. Hard to tell as we were eddied out on river right just above the house rock. I would guess someone hitting it might have dislodged it and ended up running that slot buddy style with the log... No fun!
Glad to hear it's gone. That doesn't surprise me given the hoki-poki dance it was doing. Might be worth looking in the slot to make sure it isn't stuck in there under water next time someone paddles down, especially as the level looks to be dropping for the next week.