The double action pull is much lighter. I suspect it was just that along with enough on the grip safety and trigger to enable a fast double-tap. Unless you feel out of control with it I wouldn't give it a second thought.
"a fellow in prison right now because his weapon went full auto for three rounds, and the BATF found out about it (I don't recall how) and prosecuted him for having an unlicensed machine gun"
I call BS: The BATFE don't give a rats about a malfunctioning weapon. This is fear mongering. The only way he committed a crime is if he intentionally modified the weapon to be full auto. Proving intent pretty easy when it comes to machine work and a real gunsmith would know the difference between intentional mods and a malfunctioning weapon. Additionally, unless the gun was used to commit a crime, the BATFE will generally confiscate the weapon and kill you in court for tax evasion. IMHO they'd rather get your money than throw you in prison.
As a person with an NFA trust and several covered weapons, I gotta say this kind of post is ridiculous.
I call BS: The BATFE don't give a rats about a malfunctioning weapon. This is fear mongering.
David Olofson is a U.S. Army veteran who was tried and convicted by the U.S. Federal government on the charge of "transferring a machine gun" after he lent his 20-year old AR-15 rifle to a friend, Robert Kiernicki, and it malfunctioned on a shooting range, emitting multiple rounds and immediately jamming three times in a row, which aroused suspicion that the rifle was in fact an automatic weapon.