Selecting a track, then changing tracks but the first track is still playing through headphones

Hi, I recently bought a DDJ 1000, which is a great piece of gear, but the one flaw I've found is that, very occasionally, when I select a track to play through the headphones, then change it for a different track, for whichever reason, the first track will still play through the headphones, even though it's not selected in rekordbox as the song for that channel.

Has anyone else encountered this? It happens quite infrequently, but it could be a set buster, if it happens when I'm playing live.