So, I thought it was a foul immediately, but now I am not sure. In fact, I've convinced myself that it's a good hit. This is the top view. If the 8-ball is hit last, the immediate motion off the 8-ball would have to follow the tangent line toward the brown area near the side pocket or it would stop I suppose. If it's a good hit, then the cueball will immediately follow the tangent of the 4-ball. That would be towards the yellow/green area, which is exactlly where cueball went. Maybe others see it different.
Why did Yapp hesitate and just stand there? He sent me a note, so this isn't conjecture. He knew it was really close and was waitng for the ref to confirm. The confused look was that the ref didn't say he won the match, so then it went through his head that maybe it was a Race to 13, and he didn't realize it.