I get this often, from stress. It feels like I need to 'crack' something, to get me neck back in shape, but it's really muscles tensing up. Once I get through whatever is stressing me out, things seem to go back to normal.... for the record, I'm 40 too ;)
I never played Major ass mask. As a kid the idea of only having 3 days to do shit stressed me the hell out. But now I'm a grown ass man with grown ass problems and bills. Nothing will stress me out. I will play it and I will beat it and it will impress girls and it will be sick.