No kickback through the handle, but the log may flip back up at you, especially if the knot is at the ram end and not the wedge end. Any crotch/stump or anything with a knot, I take a step back as I pull the lever.
Just like DaveC said. Nothing through the handle, but it will toss a stick up or out if you're not carefull. I've done the same on my hyd unit while pressing through a hard knot.