I had several mbp during the past, and now. My last one is from late '13. All of them, as far as I can remember, when I put them to 'sleep' mode, they keep being a little bit warm. Slightly warm, nothing special. I thought this is normal, and possibly is. But a friend of mine, with huge experience in pc's (but not in apple), told me that this should not happen. He told me that even though the electricity is present in my mbp, it should be cold. If it is not cold, then maybe something(process?) 'keeps' my mac 'active'(besides sleep mode) and maybe this is the reason for not being cold. What is the truth? What should I expect about temperature, when I put it on sleep mode?