UPDATE! Feature or Bug?

ZombieRush brought it. DUH! RTFM! Right there on page 16 it says it will do just this:

WARNING: DO NOT USE EXCESSIVE UPWARD FORCE
WHEN INSERTING A LOADED MAGAZINE INTO THE
PISTOL. EXCESSIVE UPWARD FORCE COULD CAUSE
THE SLIDE TO MOVE FORWARD, CHAMBERING A ROUND AND
MAKING THE PISTOL READY TO FIRE. 

Power is back on! So you decide. S&W M&P Pro Series. 9mm in slide lock. Attempting a reload (with dummy rounds of course!) Here is what we get. 

I DID NOT engage the slide stop lever. It does it all the time unless you carefully hit the magazine buttplate at a 90 degree angle or do not use as much force. This is the primary Firearm going with me next weekend. It DOES load a cartridge when this occurs. 

I will have my trusted M1911 as backup. So is it a bug or feature for timed competition?