Maybe you need a little more Restylane to see results?

I don't really know how deep your marionette lines were to begin with but sometimes people need more to achieve desired correction.  If your doctor used any type of dental numbing blocks in that area to reduce discomfort that could cause some swelling and distorion of the area during the treatment.  If that were the case then perhaps the area was undercorrected which means that not enough filler was used to get the level of desired final correction. 

Normal swelling from the filler would happen for a few days after the treatment (which made it look good), then as the swelling diminshed then you actually see the true correction from the filler. I would suggest to follow your doctor's advise and schedule a follow up visit.