Veritas R8 Problem

This evening my Veritas R8 decided to emit a loud 'beeping' noise on
its external bell. The alarm was not set and no internal alarm
sounded. I was unable to reset the external bell. The only way I
managed this was to trip the tamper alarm and then perform a user
reset.

I can't help but wonder whether it was some kind of warning indicator,
e.g. battery.

I'm just a bit worried that this thing will go off again at 3am.

The alarm has smoke detectors and in the installation manual it states ..
Telecom, Cabling and VoIP continues...