Pressure build up in Ferementation chamber

So I got to thinking this morning and while I don't think there's an issue, I figured I'd ask the more experienced.

I just converted a chest freezer to a fermentation chamber. Does a great job of maintaining temperature and is rarely on. The only negative thing is that I need to buy more carboys to fill it now (17+ cu ft). And while as a newbie I like to lift the lid for a bit and look at the airlock bubbling away and the look of the krausen, I often get a good whiff of CO2. That burning sensation in the nose that lets you know fermentation is occurring.

So....has anyone ever have a fermentation chamber blow a seal/gasket/lid due to CO2 build up?

I run an external controller and the wire goes between the gasket and the collar so there is a little gap on either side of the wire to "vent". I also think there will be enough "leaks" to let the pressure vent around my collar and faucets (it an old keezer).

Thats an interesting question. Im Fermenting just one 6 gal carboy of Hefe in mine right now. I tell ya if I stick my head down in their to look at it I have to hold my breath. Not cause it smells bad but because I get out of breath lol. Maybe its in my head. Co2 is 1.5x as dense as air so I dont think it should be much of a problem. Especially if you like to take a peek now and again lol