Did you let it sit 25 hours in a warm ventilated area? It may not have been as dry as you think. How much have you handled that part of the sling with sweaty hands?
Sometimes there are chemicals and other contaminants that will come out after you oil leather. If you oiled it and it now looks dry, you may want to put a little more. Sounds like the leather dried out and absorbed something the oil is releasing.
While I am thinking about it, clean your boots and let them sit at least 24 hours in a warm spot with air flow. Not direct sun. Go to Tandy leather and get some Black Fiebing's Pro Dye and some Resolene. The Resolene will put a littke shine back on them if you put several coats. Super Shene will work but soaks in a little more and not quite as shiney IIRC.
Check Tandy Leather's website for directions. There is Tandy store right there in Round Rock. If you take the boots, they can probably help you better pick something to get them looking good again.
I am really going to try and be at the range Saturday afternoon and evening. Not sure what time.
Sent from my SM-S906U using Tapatalk
