Scabs and sores

i had ORIF surgery and then was in a hard cast for 4 weeks. I got out if the cast and into the walking CAM boot on Friday. I have 3 scabs on my injured foot. One on the left of my heel, one on the back of my heel, and one on the middle of the top of my foot. Is this normal? Should I be doing anything differently? Are they from swelling?