safety – USB miner and risk of fire

I wanted to try-out mining from a pool from a raspberry pi. I ended up buying a USB ASIC miner (not sure I can post brand here). It’s a bit bigger than a USB drive and mounted with heat sinks and fan. It is connected to a USB hub which is powered separately. I think it draws about 10 watts ( 5v x 2A)
My question is, if I let it turned on all the time, does it have a risk of fire? The electricity in my house is reliable (wires are safe), but I’m concerned about the heat. Or any other risk it starts a fire while I’m sleeping (for now I’m not letting it on when I leave the house).
Am I being paranoid? Any particular recommendation?