This may be a new cyst adjacent to the original cyst. If the cystic lesion that popped contained sterile fluid than it should become absorbed by the body usually without incident. If however the cyst was infected or inflamed it can cause an infection and may eventually abscess. Some abscess can become serious and cause septicemia (blood infection). In either case it would be best to have your cat examined by a vet in case it is the infectious type.
This is the expert forum and we generally wait for the doctor to explain things.
All I know is so much depends on the type of cyst and whether it was a benign fluid-filled cyst or something else. Is it safe to assume the cyst removed last year was benign? Did the doctor explain what type it was?