With the grill mat there, you should be good. I was nervous and made a tile pad with 12x12 tiles and a 2'x2' sheet of plywood.
also helped keep boilovers/drips off the wood deck.
Primary: English Mild
On tap: Pale Ale, Lancelot's Wheat, English Brown Ale, Steam Beer, HoovNuts IPA
Bottled: MOAM, Braggot, Raspberry Melomel, Merlot, Apfelwein, Pyment, Sweet mead, Cabernet
Gal in 2009: 27, Gal in 2010: 34, Gal in 2011: 13, Gal in 2012: 10