Ok, if you have a hood or a light on the hood or a light at all, it could be the light.
I bought a hood with a light at petco and they have crickets running around loose so when I bought it, it had dead crickets and cricket crap inside the light in spots that you can't clean. Now, when my light is on for an extended period of time, the stuff heats up and it smells like burning crickets..
The smell should fade over time.