nothing is wrong with your vamo. mine fires for a fraction of a second after the button is released. not a flaw. just keep hitting on it until it stops. actually, IMO its better to keep hitting your PV even after the sizzling stops in an attempt to clear the remaining vapor from the juice delivery system and drip tip. the reason to do this is because if you dont, youll end up with more condensed vapor in the juice delivery system and drip tip than if you did not "clear it". this results in more of a liquidy mess in your drip tip, which rolls back into your juice delivery system. and vaping backwash is never top on anyones list of things to do.
my opinion is that folks are not noticing the tiny fraction of a second worth of vape at the end of each drag. of course its possible that they dont experience the extra bit at all, but my guess is that its happening and they dont know it. thats what happened with me. when i first got it i didnt notice it at all. then all of a sudden one day i just noticed it. and now that i have, i cant go back to not noticing it.
Not so simple with atty's though. If you keep inhaling after it stop sizzlings you'll actually pull in some juice. Cartos and clearos you wont. So figuring out when to stop inhaling on an atty becomes a task now.