Well, first of all, you shouldn't be leaving your iguana out unattended... As you will soon find out (if you haven't already), iguanas are very good at finding trouble when left on their own. It is entirely possible for your iguana to get into a situation while you are away that would be life threatening or could knock over his heat source possibly setting your house on fire... It's not worth it. It's fine when you are home, but not when you are away.
About a year and a half ago, my iguana knocked over a milk crate in his outdoor cage and scared himself to the point that he managed to charge through the bars of the crate and got stuck with the crate around his body in front of his hind legs. I had only been gone long enough to go to the bathroom... When I went back outside, I found him doing alligator rolls trying to get free. Fortunately, I was able to calm him down, and eventually cut him free with a dremel tool. I'm sure that he would have been much worse off if he had not been found for several hours...
Also, the older and bigger your ig gets, the more trouble they can cause... You have to keep in mind that iguanas are used to climbing, and I assume most of the stuff in your house was not designed to be climbed on...
>>Well... I put my ig on his palm upstairs in the bathroom as usual and left for class (which is only 2 hours long). When I returned home I went upstairs to the bathroom and he was no where to be found.. Then... I noticed something moving under a rug in the bathroom and found my Miles sitting there looking freaked out under the dusty rug. Could he have hurt him self or harmed his lungs? I gave him a bth and put him back in his cage... He seems to be fine but a little traumatized. After all he is only about 7 months old. What should I do?