Monti cap help

[Jhoussock]

i put this monti on the top of a live rock about four weeks ago in my reefer250 and the sucker really took off. The darker lumpy center is about a year old and the lighter edges is the new growth (about four weeks). Last night I noticed the white spot/crater. I’m usually pretty good about noticing things like this so it’s either growing fast or it happened all at once. I’m pretty sure I saw a hermit crab hanging out up there the other night...is this just an injured spot I should keep an eye on or is it something I need to treat in someway? Forgive me if this is a stupid question I’m pretty new to all this and this is my first issue with my coral
Lighting is tuna blue kessil
Salinity 34ppm (apex and refractometer measured)
Calc and alk normal (Hannah checkers) 450 and 9dkh

 

[Jhoussock]

The picture isn’t very clear and looks like a growth but in real life it’s more of a crater that is con-caved into the Coral not bumped outward