I suggest you ask your contractor to come back and check it for your piece of mind. Wood will burst into flames at about 451 F - it is extremely unlikely the outside of your oven is anywhere near that hot. My guess is that the temperature of the outside is well below 200 F - otherwise you would not be able to keep your hand on it for 5 seconds. Your contractor should use either a IR thermometer , or better yet a contact thermometer to check the temperature of the case after the oven has been on an hour or so to make sure there is nothing wrong with the oven itself. I doubt you are missing a shield, but if you have the model number, you can go online and find the installation instructions and read them to see what they call for.