Last night I plugged my phone into an outlet to charge overnight while I went to bed. In the morning, I woke up (NOT to the alarm I set on my phone, I might add), and found that, while still plugged into the outlet, the phone had shut off.

Does anybody know why this happened and what to do to keep this from happening in the future?

I've seen other reviewers of the LG Extravert complain of a similar random shut-off problem, but I've had my phone for only 2 months, now.