What could be causing the air pocket on one side of my nose? Over 1 year post op

In general, bulges like that may represent irregular tip cartilage from previous rhinoplasty. Since you may have thick oily skin involving your nasal tip, it's possible this is just redundant skin. If your surgeon is unable to provide an answer, please consider consulting with another reputable rhinoplasty specialist. Wishing you well moving forward. Sincerely, Dr. Joseph

That looks more like tip cartilage than an air pocket but an in person examination would really be necessary to determine that

This looks like a scar tissue or cartilage caused deformity of the tip. Only on the basis of in-person evaluation one could give you a more detailed answer. You should seek explanation from your surgeon. Good luck.

To make a quality assessment, we need quality information.
I don’t think anybody can give you a good answer based on the information provided.
I suggest you follow up with the surgeon who did your rhinoplasty if you have concerns about the outcome of the procedure.
Best,
Matt hagstrom MD