Yea. When you close the type cover it registers a sleep command, like a normal laptop. So I think by pressing the button, and closing the cover, as it is not an actual button system by rather some sensor, it sends a "cover open" at some time, so it wakes up the system. That is my assumption. So basically, choose, close keyboard to sleep, or press button. Don't do both. However, I must say, I don't have this issue on my side (trying it now, and not doing what you are experiencing. note that I di dnot install the Jan firmware update, I have the October one, everything works flawlessly so why upgrade?)
The lot number of my surface pro 2 is 1401, and the type cover 2 is 1345 if you wonder.