DI Canister floss is black
 

My DI is simply 2 tubes inline after the RO membrane. There is non-removable floss on each end of the tubes. The first floss pad is white (the one that the water passes through before passing through the resin), and the other three are black. I soaked them in vinegar, and used a spray bottle to squirt the pads, and they have lightened up a little bit. Should I be concerned about this? Potential for contamination? Should I just tear them out (they are secured down, maybe glue, and then there is a plastic grade over it), and put my own floss in, or is this not necessary?