Yeah unfortunately I'm well aware of boards closing up on rip cuts!
Years ago I had a pretty scarry kick-back on an old contractor style table saw! It was with a 4-1/2 foot piece of green rough cut red oak that twisted as I cut it, luckily I wasn't hit by the piece since it had enough force to knock over a cart about 6 feet away.
That's another reason I wanted a newer style table saw with a true riving knife/splitter assembly that goes up & down with the blade.
Doug