Is this a premolt or normal coloration?

[JGarrick]

I have a Aphonopelma chalcodes sling that I picked up the other day. I've never had a sling so tiny before and I'm not too familiar with this species when they are at the 1/4 inch range.
Is the black spot a normal coloration for them as slings or is it a premolt? I have a picture from when they were first born/hatched/emerged or whatever and put in their cups for reference but I'm not sure what it is.
I had to rehouse the little thing because this sling is one major burrower even compared to his sac slings and it immediately dug a burrow to the bottom of it's little enclosure, over an inch deep and has made a little den down there and closed off the opening.
Not sure if that's normal when you rehouse them either or if it's premolt stuff.
About how long do little slings normally stay in premolt on average have people noticed?

 

[cold blood]

The black spot is the urticating hair patch.....its normal for most terrestrial slings. Its not a sign of pre molt....when in pre molt, that black spot will expand and eventually take over the whole rump....in the latest stages it will also have a stretched out, shiny look.

 

[Vanessa]

This is a burrowing species, often even as adults. It is definitely normal for them to burrow as youngsters, though. They can barricade themselves directly after moving, that is normal. They also barricade themselves to moult. This is an extremely slow growing species who can fast for a long time, even as spiders. That is the trade off for a spider who could potentially reach 40 years in captivity for females.
The black patch is their urticating hair patch. That can go very black in spiderlings, but that going black alone is not indicative of pre-moult. The entire abdomen will darken. Your little tyke looks good.