Is there something wrong with my Hongi ?

[origin6]

Hi guys my hongi male is doing something weird he is not the only hongi male but he is the biggest and most dominant of the hongi in my tank he seems healthy he is eating well and defend his territory well but has started to sorta swim backwards in short bursts while sorta gumming his mouth looks like he is chewing on something, is really hard to explain so here is a video of him doing it its right at the end of the vid sorry for the out of focus when he does it but i think you will get the idea.

http://s1113.photobucket.com/albums/k520/origin6/African%20Cichlid%20album/?action=view&current=DSC_0087-1.mp4

[origin6]

No ideas if this is something to worry about?