Pimple or broken stitches? (Photo)

If it is along the incision, it most likely has developed from a spitting sutures, possibly a small suture abscess.  Consider moving up your appointment, not because this is likely serious, but just for peace of mind.  Best wishes for an easy recovery!

Thanks for sharing your picture and situation.  Since the "bump" is on the actual incision line, it's a good assumption that it is related to the incision itself, and not a random pimple.  The most likely scenario is that it is a deep dissolvable suture, such as a vicryl, that came too close to the skin and wants to "spit".  Rest assured, it should not effect your final result, but it should be looked at by your surgeon. If it is indeed a spitting stitch, then it is easily removed in the office usually not even requiring local anesthesia or oral antibiotics.

An examination of you should be able to determine if the bump under your chin is due to a pimple or a suture after your recent surgery.  Since the bump is right along the incision, I would say that it is possible that it could be due to a suture.  Your surgeon should be able to determine the cause and be able to treat this issue.  I would contact your surgeon to let him or her know about your problem and it is possible that they may want to see you sooner.  

It's difficult to tell from your photos. I recommend following up with your Doctor. Keep in mind, it will take up to 6 months to see final results after a neck lift. To improve final results, we will often do a kybella and ultherapy about 4-6 weeks after neck lift to get more of an outcome. See an expert. Best, Dr. Emer