There is always a risk with dark denim transferring color onto anything. Thats not the fault of the bag. I would recommend that you cclean your bag and condition the worn and then spray your bag with a few coats of protectorate spray if you want to keep it looking new for as long as possible.
When left untreated, crunch leather's color will fade a bit, the shine will dull slightly, and the leather will soften quite a lot with use. The result is a asoft, distressed look. Many of us let our crunch bags age naturally and love how they look even better with use (myself included). Others do treatments to keep them looking new when we buy them and then retreat them every couple of months.