I received my Puck a few days ago, it's a great product. I'm really impressed by the quality of both the PCB and the plastic/silicone case. The assembly fits together really well.
I got started really quickly as described in your Puck-Js unboxing video. I've run through the basics, your puck2.html example, Puck.mag() and Puck.light(). Everything was quick and easy as advertised.
I have hit one snag as a result of playing with Puck.light() (not directly related to that function though). While trying to block the light to the sensor I must have blocked the signal because I lost the connection. Once the signal was re-established I couldn't pair with the device again.
I'm using a Chromebook to pair with it, so I disabled/enable the Bluetooth hoping it would reset the connection. I also tried restarting my Chromebook, both attempts were unsuccessful. I could still see the Puck in the device list but it just wouldn't pair.
Eventually, I removed the battery from the Puck and all was well again. I repeated the problem several times with the exact same result.
My novice guess would be that once the Puck has paired with a device it will persist with that connection and not timeout or enable another connection. Or is it a problem with my Chromebook?