Thanks for the suggestions! I played a LOT with the Youtek SpeedPro (which is VERY stiff) and that's when the pain started to ramp up. I have recently switched to the Volkl C10 Pro which is very flexy, so we'll see if that helps.
I don't claim to be an expert at 4.0, but I don't think my technique is the problem, as the problem is fairly recent. We'll see if the Volkl flex fixes the issue.
"I think the myth of the pusher is actually the tale of the sore loser." - GuyClinch