TFAME
Not sure what you mean when you use the expression "The North Atlantic Track", because there's more than one track and they are not in the same place every night.
In a nutshell there are designated North Atlantic Tracks which change on a half daily basis to cater for traffic flow( Westbound Daytime, Eastbound nightime) and the position of the jetstream(s). You normally end up with around half a dozen published Atlantic Tracks and depending on the Tracks on the night it's perfectly possible this flight was on one of the Southerly Tracks. It's also perfectly possible the flight was crossing the Ocean on a non-NAT route, otherwise known as a Random Track.