What is this on my A. sp. amazonica?

I was looking at my T's when I saw my A. sp. amazonica grooming, I walked over and looked and seen this, any ideas what it is? The spider is about 1.5-2", acting completely normal.

It looks like a tick.

Ticks aren't parasites of tarantulas.

Good question, mate? I can't make out if that's litereally a hole in the exo, or something growing on it. In either case - was that there before the last molt? I'm assuming it wasn't, else you would've probably kept an eye on it. Hoping the T gets rid of it next molt, or someone can shed some light on the subject otherwise to help the animal.

I don't think it is a hole, from what I can see, it looks like a 'scab'. I don't think it was there but I may have missed it.

From the blurry pictures it looks like the coxa didn't fully become sceloritized after the last or another previous molt. The white region looks similar to the chitinous cuticle that makes up the leg and pedipalp joints. Unsceloritized cuticle is white and flexible because the chiton has not bonded with the compound scelortin.

Also the affected area does not have setae which leads me to believe all layers of the new cuticle didn't form correctly before a previous molt which would explain why scelortization didn't occur fully there. Perhaps it could go as deep as a problem with the epidermal cells producing the new cuticle. Either way, the problem should correct itself over the next molt or two.