Shaking? Fluttering?

[sayitfast]

So I was watching my Discus just a bit ago and one of them started fluttering his/her lower fin... I've never seen this before... is this a sign of something I should know about. It was very obvious and lasted maybe 5 seconds or so.

These are my first Discus I've only had them few weeks... there fairly young maybe 4 inches in length.

Thanks

[judy]

Could be just a little dominance display.