I have my Flash Plus 2, too which I'd got 5 days ago . I have the original charger and there's no notification when charging. My cel got fully-charged in 1 hour while ads' said get fully-charged in 30 minutes.
From what I know, it's the batteries capability that allows fast charging. Samsung has that capabilities. It is not the charger, it is the battery.
Some phone companies had discover that already. 10-15 minutes charging. For Flash Plus 2.0, I am sure it is only in the advertisement. But not the actual unit.