getting warm while surfing, that's different.
maybe you have a defect piece, get it replaced and see if the new one still get hot.
I recovered my ipad2 backup when i got the new ipad while on the charger, it did get warm but nothing similar to most complaints here.
I think a lot of people overdblow things: i have owned every single iphone, ipod and ipad, and never had ANY of all the problems that used to be reported: anntena, or screen, or heated .... NONE.
just relax everybody, give apple and the app builders some time to maybe tweak the IOS or their apps to use the graphic processor in a better way, and heat up less.
just enjoy that retina screen and HD camera 🙂