what is making it upset? i've never had a puffer - but wouldn't seeing an angry or stressed animal not be a good thing? Do they just do that every once in a while like some fish yawn?
whatever the case, it looks neat!
BTW, it looks like you have a bit of cyano or dino bloom there on your substrate (not knocking your reef-keeping skills or anything - I'm battling it a bit ATM myself). Most folks suggest you decrease your photoperiod, cut down on feeding, put flow on it (a powerhead or two angled at the front glass towards bottom of the tank can push a LOT of detritus back into the water column so that it won't accumulate)
When I had my 55g, I'd do a weekly 5gallon water change - I'd siphon my substrate - and that seemed to help out A LOT.