Sore Gastric Band Port 4 Years Post-op

Yes the tube from the port can “poke” the muscle  as it enters the abdominal cavity (sit ups do this), if it’s not too bad and  goes away quickly after  you do your exercise, just place local heat in the area 15 minutes three  times per day. The only other option is to change the port locationn (outpatient  procedure usually done with local anesthetic) 

This can happen at times. 
Sometimes we close the portsite with a stitch which can cause discomfort
later.  You tend to get more pain on the
side port (below the ribs) than the middle port.

It is very unlikely that your port would start moving around 4 years after surgery.  By this time the port is well encapsulated and shouldn't move.  You probably have pulled a muscle from all of the exercise.  If difficulty persists you should see your doctor.