If he didn't snore before, but he's snoring now, there's a reason...did he gain weight?
You'll need to check with a doctor for the reason.
You can also try an over the counter snore stopper, it's a spray that's sold with the cold medicines...my boyfriend has used it and it works pretty well.
Does he stop breathing while he's sleeping...if he does, he has sleep apnea, and really needs to be seen by a doctor...it could damage his heart in the long run, and his overall health.