Question: Macbook screen goes black, low battery icon appears even when charged
I have a Macbook Pro retina (2013) and the machine has been great! However I have noticed lately that after closing the machine (not powering down, just closing lid), when I reopen it, the screen will be black and the low battery/plug in to power icon will appear. I plug into power as I can't 'wake-up' the machine any other way, and once power is plugged in, my battery level is always fine (ie anywhere from 25%-80%). Is this a sign that my battery could be going out? It's starting to be a slight hassle...at the same time, I don't recall this happening every time I close the lid & put the machine to 'sleep' - only sometimes. Any ideas/thoughts would be helpful. Thanks!
MacBook Air, Mac OS X (10.7.2)