Does everyones air get hot after an hour of heavy browsing?
Not me but it probably depends on what "heavy browsing" means to you.
Are you running flash video's or youtube stuff? That makes an mac work pretty hard.
When you say "hot" how hot is your system getting? Things like istat can show you actual temperatures.
My system is running about 130 degrees fahrenheit right now.
The warmer a mac gets the more aggressively the system will run the fans.