Is it normal for your arms to still feel hard and bumpy after 3 weeks of armlift?

Swelling, tightness, lumps, bumps, numbness, etc. are common findings after arm lifts and other procedures, especially if you had liposuction performed at the same time. All of these findings can wax and wane during the recovery process but generally they tend to improve over time. Gently massaging these areas can facilitate the process but I would recommend checking with your surgeon to make sure that your incisions are healed well enough to begin the massaging.

Induration and hardness are components of the normal healing process. By now, these concerns should have resolved themselves. If there is anything suggestive of a fluid collection, hematoma, infection, or blood clot, see your plastic surgeon.  Kenneth Hughes, MD, Board Certified Plastic SurgeonLos Angeles, CA

Yes it is possible to have lumps after surgery,  the healing process takes time and you will see these changes occur over time.  At only 3 weeks is possible to experience changes as you describe.