I have a mid 2009, 13" macbook pro, and when I use it in my bed, I make sure to put it on something that doesnt bend, like a slim large book with a hard cover,

I have a mid 2009, 13" macbook pro, and when I use it in my bed, I make sure to put it on something that doesnt bend, like a slim large book with a hard cover, or a plastic tray. I don't really know why it gets hotter over the year. I guess fine dust end up clogging it, and since laptops are very slim, everything is packed, so it might be pretty hard to remove that dust. Some dust can stick to some surfaces, but I'm not sure. One thing for sure is that I wont use it for gaming or anything that might get it hot.