BRL,
I have run into a similar problem, but I have had an unbiased person help me with this. Tandy people are salespeople first and for most, so they have to sound like experts. I went to a friend of mine for some help and to figure out way this is happening. He is a artist/painter, who works primarily in acrylics, and after a few days of having my Cova Colors he deduced:
1- In order to maintain flexibility on the leather without cracking it has some latex mixed in, which is pretty sticky.
2- They are sold in a very heavy bodied consistency and can be mixed with a fair amount of water before applying it to the leather. * Warning more water equals lower latex level, therefore less flexibility*
3- They are cheaply manufactured, so you are best off only using it with brushes and not an airbrush. Liquitex brand paints, like Basics acrylics, thinned down a little clog an airbrush less frequently.
Either way I have found after applying the paint, coating it with satin shene and then using an atom wax or leather balm the only sticky feeling is the initial waxy one from the carnuba (misspelled I know) wax.
I hope this was helpful,
Dave.