Do You Guys Spray Your Racks w/Something Non-Stick?

I'm curious if I should be or not.  I've been cooking right on my racks as I was instructed and at first this wasn't an issue.  I clean them when I'm done each time but as they get more 'seasoned' it seems that the bark wants to stick more now.  I'm smoking a pork shoulder now and just went to pull it off at about 178deg and about a 25% chunk of my yummy bark from the side that was down came off the pork and stuck to the grill rack.  I swiftly and deftly scraped it off and grafted it back onto the shoulder but I'm not sure that's ideal.  Do you guys spray Pam or some other non-stick product before placing your meat on them?  I always have a heck of a time prying these off the rack so maybe that's a little pro tip I'm missing out on.