Why Did the Shape of my Mouth Change After Rhinoplasty?

A pre and post photo will be very helpful.  The likely cause is the deprojection.  If as you say your nose was large and projecting, you would have grown up with the appearance of a relatively shortened upper lip as the forward thrust of the projecting tip pulls the upper lip forward and makes it seem shorter on front view.

If there was a substantial deprojection of the tip as part of the rhinoplasty, then it can have the effect of relatively lengthening the upper lip as the projecting tip sits back into the face more and takes the forward pull off the lip which can then drop.

Usually, this is an effect we actually try to create.  In tension noses, the lip often looks short and by deprojecting the tip the nose looks better as does the lip which has the vertical strain taken off it so that it can sit more naturally and longer.

Your procedure will not have lowered your bottom lip position.  If the effect which has occurred in you is not to your liking, a vertical lip lift should be able to correct it.  Again, to confirm that you'd need to post some pictures.

Hope this is helpful. Good luck.

Photos would be very helpful in order to address your concerns\

send before and afters

Sometimes with a large dorsum and tension tip, the lip is pulled up a bit showing more teeth.  Possibly with the corrective surgery, the tension on the tip was reduced and the lip relaxed. Often this is a good thing bringing the face into better balance.  Photos would be helpful.

 I have performed Rhinoplasty for over 20 years and IMHO, if you are able to move your mouth as before the Rhinoplasty, no harm was done to the motor nerves or muscles.  The position change and/or length differences, of your upper lip, are most likely due to the changes in tip projection...but as always, you should discuss this further with your Rhinoplasty surgeon.