Hey guys I been buying my a few E juices from Nicoticket and a local shop near me. All are clear in color when purchased. Then when I take my vape to work and leave it in my bag and use it during the day, It is becoming Dark brown very dark brown. I dont know why or what is happening. Is the juice still good this way? Or should I replace it when it gets like this?? Also how do I stop it from doing this? Thanks guys