This has happened quite a few times after I bought my MacBook Pro back in July 22, 2013. Sometimes I, inadvertently, do a random gesture with my fingers on the trackpad and the machine puts itself on sleep mode. I have tried a simple search about this but I haven't found somebody with this specific situation or I don't know hot to call it and therefore I can't find more info. Please, if someone knows anything about this I'll be forever grateful!