We have a sub-zero 650 with a bottom freezer. The slide out drawer has been functioning poorly for the past week--it feels like it's sticking. I've been pushing and pulling it harder than usual, hoping that it was just a matter of something that had been shoved in there improperly (teenagers!), but the problem continues. Today, I got down on my knees to check it out. There's something black and icky looking on the track that the drawer slides in and out on. Could this be mold? If yes, what do I do about it? Should I be worried?

(I posted this in appliance forum too--hoping for a fast assessment and solution! Thanks.)