Got a surprise today when the LBS called and told me I could pick up my bike. I talked to the mechanic and he said he definitely was hearing the noise. Under guidance (I think) from Spec's warranty group he disassembled everything in the motor case and reassembled it carefully, being sure to torque properly, etc. He did not find anything specific, but since putting it back together several people went out and rode it hard and the noise hasn't come back. So I can pick it up and start riding it, with the commitment that if the symptom comes back, they will immediately swap out the motor.
So once again I'm happy with Specialized and especially with my LBS. I'll have to wait until tomorrow to get it and will be anxious to try it out.