Anyone have bad battery days? My battery is nearly always fantastic, end of a full day it is "never" below 40% and normally closer to 50-60%. "Never" except a total of 5 random days since release when for absolutely no apparent reason it has died completely half way through the day. Had another day like it today, absolutely know it was 100% start of day and nothing different about usage at all today, yet it was off by 3pm. Anyone else had this?