I'm 24 days post op chin lipo. My PS said this is normal. Is this swelling or residual fat? (photos)

Swelling at 3 1/2 weeks post operation is normal, and you should not be concerned. Give yourself 6 weeks or more to heal and view the final result.
However, your chin lacks projection, which is attributing to the presence of double chin. Perhaps considering a chin implant will allow you to achieve your desired look, rather than more liposuction
Gary Linkov, MD.
Facial Plastics Specialist
Manhattan

You have swelling, which can last for weeks following your procedure. To speed up healing, you can try adding Venus Legacy or Exilis radiofrequency treatments. To improve final results, we will often do Kybella and Ultherapy treatments about 4 to 6 weeks after VASER Neck Liposuction. See an expert. Best, Dr. Emer

 Six weeks is a reasonable timeframe to judge early liposuction results. You're not quite there yet. It appears that the folds you were showing represents skin when flexing the neck  Do you have a fairly significant recessive Chin that lacks projection.  This is the primary reason you had a double chin and asked for liposuction.  The definitive treatment is a chin implant or sliding genioplasty. Without addressing the primary underlying cause which is skeletal your results will be limited from soft tissue manipulation only.  I would be surprised if this was not brought to your attention during the consultation especially if you consulted with a board-certified plastic surgeon.  Best, Mats Hagstrom MD