MacBook Pro heating up
Just recently, my MacBook has been getting really warm when using it. It's a 13 inch, mid 2012, running macOS Sierra 10.12.6. Is this normal? It's hottest on the bottom, left rear corner, but the keyboard surround is also warm. It's sitting on a plastic mat designed for laptops, on top of a wood desk. It does not get hot while charging.
Thanks for any help.
MacBook