Called Rohrbaugh today, and was told to send the gun back so they can diagnose the problem.
While that response was predictable, one thing was surprising: I was told not to clean the gun if it hadn't been cleaned already. I didn't think that most gun makers would want to mess around with a dirty gun, so I had cleaned it, not realizing that seeing the gun in that condition might provide information.
In my case, it won't make a difference. The malfunctions occurred at the same rate during the last magazine as during the first.