Thats OK, I figured that was the case. I think you're worried needlessly here.
Think of it this way... Your car sitting in your driveway will be about the ambient temp of the time, When you drive it it does warm up and the design of the engine dissipates the heat through a cooling system. But lets say you've got a leak in a hose so the coolant leaks out doesn't your car tell you its time to pull over? The temp gage and warning light should tell you.
Well, your iPhone is doing the same thing it will dissipate the heat as needed and if the phone is overheating it will tell you with a warning and then go into safe mode shutting its self off if you don't quit the app/process thats the cause or place the phone in a cooler location in case you've got it cooking in your cars window.