It could of but to be honest I am still using the cloud. Only once with a friend right when we put the ELB in and turned the unit upside down, vapor was coming out of the bottom, it didn't really smell like weed. I think it could of been trace ISO left on ELB. I know it could be unsafe to use the cloud because of this, but the vapor is as pure as ever taste wise. I am not so concerned because this smell only comes when an ELB is in, it could be the particles on the outside of the ELB burning. I'm gonna clean it and put it to the test today. I'm concerned the heating cover moving down can happen with any cloud, I hope not.
Nosferatu - there is a little play when it comes the the glass. We tighten it down quite a bit but there is still just a little play which is causing the glass to slide up and down. If it happens to me, I gently pull it back up. Usually it gets pushed down if someone is using too much force when putting the HydraTube on top so just let people know not to press down too hard on it. Just let the weight of the HydraTube sit on the Cloud. If it becomes too loose, just file a support ticket and we'll take care of you.
I have a strong hunch that something got into the glass tube which was causing that smoke/vapor/smell. If you decide to swab the glass with iso/water, make sure it has cooled down before you do so. After you swab it, I would turn the machine on and make sure that everything has evaporated. If the taste is fine, then I feel rather confident that none of the contaminants are getting into your lungs. Keep an eye on it and let us know if anything needs addition service.
As Jackstraw said - I would always sandwich concentrates within a bed of herb so that there is less leakage into the inner tube.