I have a new rMBP 13"- few days old. Twice whilst in use it went blank and restarted itself. I thought meh ok lets see. just now I am in the other room and I heard the feint sound of apple restart noise - looked in - the laptop is closed and sohuld be sleeping. I thought "oh maybe it is next door or something. Then it happened twice more in 15 mins. so I turned on the machine. The grey boot up screen came up for about 2 seconds before flicked to normal login screen. Any ideas what might cause this behaviour ? SMC issue ? What can I check myself ? Mac store is 2 hours drive away and I would not go near the more local reseller/service shop if they were paying me.