I have been using LiteCigs 510 SLB cartos for months now and I have always been very pleased with them. Just over the last few boxes I noticed something that was not happening on any of my prior boxes. It seems after a few hours of use, the "stuffing" seems to be shrinking and pulling away from the heating element, making it look as if it is condensing towards the outside walls of the carto. Has anyone else come across this issue as of late?