Moshe, some possible reasons that you stopped seeing each other on GliderLink:

1) If the phone loses it's GPS fix, it will stop broadcasting your location. This can happen if the phone is in a pocket without a clear view of the sky. I will add a notification to GliderLink when this happens.

2) If the goTenna firmware has not been updated to the latest, it may be suffering from the known problem that causes it to lose the bluetooth connection to your phone.

3) The goTenna battery may have died. This is less likely because the goTenna battery lasts quite a while.