Puffer behavior most bizarre please advice

[AkronPfunk]

My problem is my dogfaced puffer has taken to somehow folding his side fin and stuffing it into his gill...It seems to be such an unatural angle and wierds me out ,would like to know if any1 can advise me as to what this behavior is due to and should i be doing something for him

 

[OceanT419]

I have seen this time and time again and it usually seems to be normal behavior then again i could be wrong......our golden puffer does it all the time and have never had any issues with him doing in it the 3 yrs we've had him.......