Hi Dagmar,
One thing I am curious about: Normally the batteries in your SPOT will last many days, and continue to post the location of the device. Did the SPOT continue to indicate it's location with the same position reported several times, or stop reporting altogether? I'm not familiar with the operation of the SPOT, so perhaps it only reports when some preset distance is covered. Otherwise I would expect it to continue to post location information every xx minutes (based on your settings). If this is the case I think it indicates someone found your SPOT and turned it off?
Anyway, just curious.