Well, if that's not dirt then it certainly looks like mold.
I work with horsehide quite a bit when making holsters... That is NOT normal.
A few suggestions to clean that puppy up -
- lemon juice
Before you try any of those, please note that I have never had to remove mold from a holster... So I honestly have no idea what results you might get. I've just read that these solutions can get rid of mold.
If it is mold... It's worth a shot. That mold can spread to other leather items. Not much to lose. Let us know what you decide!
Hopp Custom Leather
<------ click for HOLSTER awesomeness!!
-There is no theory of evolution... Just a list of creatures Chuck Norris
has allowed to live.