Digitata - “bald patch” at top?

[PotatoPig]

I have a small Digitata that seems to be generally happy - polyps are always fully extended and it’s been growing and encrusting over the rock at a decent pace in the six weeks I’ve had it. A couple days ago I noticed what appears to be a bald spot/scratch at the very top. On closer examination there’s a similar scratch at the very top of a growth extension at the rear (can’t photograph due to location). Photos are from when I added it a few weeks ago and today.

Is this anything to worry about?

Parameters:
Salinity: 1.026
Nitrates: ~10
Phosphates ~0.2
Calcium - 420
Alk - ~9
pH 8.1
Temp: 77-78
Par ~200 at this location

Other SPS are doing well - birdsnest under similar conditions has colored up from brown to green and is growing, new frog skin acro is encrusting, two types of encrusting/plating Monti are doing well in four locations of the tank.

 

[tbrown]

Digitatas have growth tips that don't have polyps. As long as it's not white skeleton showing through or covered in Algae, it should just be growing and healthy.