This is a little bit of a newbie question, but a few months ago I put in some cypress mulch with my snake for about a week or two. Throughout this time, he would wheeze and "whistle" when I held him. When I switched to newspaper, this behavior stopped.

I'm asking because for Christmas I got him a tank instead of a tub and will need to use some sort of humidity-holding device and cypress would be perfect. Is he allergic to cypress, did I get the wrong kind, etc?