Ok, so it happened on their premesis, but what happened:
1. A fire alarm went off.
2. A fire alarm they are legally bound to have fitted.
3. A fire alarm they are legally bound to treat seriously and respond to.
4. A fire alarm they (it appears) correclty responded to.

Therefore, while a fire alarm may not be a normal/typical occurance during your stay, - it is a perfectly acceptable one.
For it not to be acceptable you would, effectivly, IMO, be arguing/complaining about the hotel fulfilling legal obligations.

The ONLY areas for comeback in my opinion would be:
1. If negligence on the part of the hotel had instigated the disruption.
2. If the disruption had been prolonged, and then hotel had then failed to continue to fulfill their role as 'host' of the guest [If you are evacuated from your own home you know the area you live in, have contacts, etc. But if staying with someone would expect them to assist you if you are disrupted in their area.]

Had a similar experience, whilst I'm not going to generalise, on that occasion it was 7 American guests (in 3 parties) who were making a big fuss, and asking about compensation the moment we were back inside (including banging fist on desk), the brits, germans, fins, austrailians etc all went straight back to bed perfectly happy with the hotel.