when I tried t dry burn one of the CE4 head today, I noticed that the wick got charred/blackened around the coils. I have no idea why this happened as it is a pretty new wick and this is the first time cleaning it. I only vaped about five or six tanks with it and didn't get any dry burns so I have no idea why it got charred. Beside, I thought silicon wicks are immune to heat. Does this ever happen to you?