I'm guessing.. It sounds like you were "riding" the slide (being gentle) Rack with authority and let the slide work as designed. If your pistol is still fresh it could still be settling in. Or, if you had been firing bulk pack 22lr prior to this failure, most bulk is pretty dirty and could of caused the failure. I would clean things up real well and try again..
When I'm clearning my pistol, I tend to tilt the ejection port down to the (right) side to let gravity assist ejection. (Barrel pointing level down range)