I have a njoy npro and use the menthol cartomizers. I also have 3 seperate npro batteries. Every time I take a pull of the e cig the cartomizer will glow red along with the led at the end. I know that inside is a heating element but I have never heard of anyone else complaining or mentioning this. Is this normal? I mean the brown looking filter will turn bright red. I don't really notice it getting too hot as I immediately put it down when I notice the whole filter glowing. Any advice??? I just feel that something is wrong somewhere. any help is greatly appreciated!! thanks