Will this blow out my guitar cab or guitar head?

I recently just converted my Line 6 Spider 3 120w amp into a head, all I did was disconnected the head from the speakers and made a box for the head. I have a Crate half cab with 4x12" speakers. On the back it says 120w or something. I played with the setup for about an hour and after I got done the head was really hot and I was a little worried. I am just wondering if a 120w combo amp head would work on a 120w cab it sounds like a really blunt question but I am still a little worried.