Some buyers of the new iPad have been reporting that it gets considerably warmer than the previous iPad 2 model. Jim Dalrymple from over at Loop Insight was able to get a statement from Apple regarding the increase in temperature:
"The new iPad delivers a stunning Retina display, A5X chip, support for 4G LTE plus 10 hours of battery life, all while operating well within our thermal specifications,” Apple representative Trudy Muller, told The Loop. “If customers have any concerns they should contact AppleCare."
In other words, Apple is well aware that the new iPad can get a bit warmer, but that is because of all the new technology that it's packing. Tests have shown that the new iPad gets about 10 degrees warmer than previous models under heavy usage.