My Band is gone for a warranty exchange by mail right now. I apparently did have a bad sensor in my HR monitor. I never checked for a lock during workouts, after the first day, my band never locked in below 70 when my resting heart rate was actually around 60. In fact, it mostly locked in a resting heart rate around 85, but sometimes it would lock in closer to 115.
My resting heart rate was 45 during sleep my first night, but for the next 10 days, it averaged 73, which is not even close to accurate.
I tried on a demo unit at my local Microsoft Store, and it locked in much quicker with a much more realistic reading, so I'm hopeful that my replacement unit will be more accurate. How accurate do the "locked" readings seem to be when you're at rest?