Yes, it’s a possibility if the cartridge is not handled properly. The Globetrotter cartridge contains various filtration media, the first being an iodinated resin which kills bacteria and viruses to the 6 log level ( 99.9999%). Iodine is a highly potent element and it will stain if in direct contact with fabrics and hard surfaces. This being said iodine is not harmful and it’s presence is something you want when dealing with contaminated water. If the Globetrotter cartridge is left standing outside of the bottle without being flushed first, there may be drainage of some excess water that has been sitting in the iodine pre-filter which could result in a stain on your counter top or favorite scarf. We are recommending to blow out the excess water from the filter assembly and cartridge before letting it dry (see the STORAGE section in the user manual that comes with the bottle). We also recommend to store the Globetrotter cartridge on its side, or the whole filter assembly head down (cartridge up).