I was going to ask about the rider in my original post but changed my mind. Since you asked about the rider... yea, being tight on the bars can cause little slides in the rear and a general feeling of an unsettled ride. You would be the first rider that I have run accross to describe it as the bike is trying to "buck" you off. Perhaps it's not quite "bucking", can you be a bit more specific as to what you feel?
Another thing is moving your bum around after the bike has some lean. Basically, get off the seat before you turn. Aka, get off early and stay there until the bike nearly straight up and down on corner exit. If you take the skill to near peak ability, you will always be on the throttle when your bum moves. You make up a considerable portion of the mass/weight of the entire operation, the suspension can't compensate for you moving around on the seat while mid-corner.
The bike has a base level of suspension ability, good throttle control keeps the suspension in a compliant range where the bike is stable. Lack of good throttle control can detract from the working range of suspension. You have one job as the rider. "Keep the bike stable." Say it 1000 times so it sinks in real good.
Do you do any of these things? Do you trail brake deep into the corners?