Hello, I have noticed that my older cartridges are not working as well. I bought a starter kit about a month ago and it came with five cartridges. A few weeks later I bought some menthol cartridges (the first ones were tobacco) and used most of them. I figured might as well use the tobacco ones I have left. So I pulled one of the tobacco ones out of the rapper and tried it out. It lasted for a few hours then overheated. Can the e cigarette cartridges dry out? 
