placing ur phone over your laptop isn't something very fatal dude.
don't worry, nothing's gonna happen.

i used to put my previous K750i over the dashboard of my car when driving and listening to MP3s via it so 80% of the time, the cell would be in direct sunlight.

the temperature in Pakistan avg is 40-50 deg centigrade, so you can imagine the heat in summers (around 55 deg C) ... nothing happened to the cell phone's life ... i used my previous k750i for more than 2 years in very rough conditions.

i didnt' changed any part, no issues faced by heat what-so-ever, so stop worrying.