My Three Year Old Son Somehow Scratched His Left Cheek While Staying at His Grandparents House and Now Has a Vertical Scar?

My 3 yr old son scratched his cheek (probably a cat scratch). It's been three weeks and the scar is pink/red with obvious indentation. My biggest concern is the indentation (atrophy) in the scar. The scar is vertical from top to bottom about 1.25 inches long. The width of the scar is 1mm.He is only three years old and kids are supposed to heal very well but I just don't see how this can flatten out on its own. I'm sure the redness will fade over a little time but the indent is just killing me.