Macbook Air random shutdown

Recently just received my new Macbook Air a few days ago and I'm loving it. This morning though I was a bit concerned because the notebook randomly shut down completely while it was in sleep mode. At first I thought it was because I was running low on battery but after a few attempts of pressing the power button it finally booted up with an error message that popped up explaining why it shut down. Wish I had saved the error message but just curious if this has happened to anyone before? I checked the battery life and I still have a few hours left on it.