Here's what I have discovered. The trigger safety spring was not engaged properly and I had what is called a "slam firing" situation. Apparently the first time I re-assembled the gun I did not have the spring turned into place (it must be turned counter-clockwise to seat). Since it was not in place, it allowed the firing pin to fall, i.e., "slam fire" after the first round.
While I have done a complete strip cleaning of this gun on many occasions, I will be definitely be more careful next time.