Read The Fine Manual.

Because you haven't told what the fire detection system is, we can't be of much help. Usually, GE uses a fire detection/protection system, or a F&G (Fire & Gas detection/protection system) which is independent of the Mark* (which you didn't tell about, either). This alarm is usually, typically driven by a relay contact output of the fire/F&G system connected to the Mark* to indicate there is some kind of issue with the system which requires attention. So, the anxiety is most likely removed by reading the instruction manual of the fire/F&G system provided with the turbine and auxiliaries, and determining what can trigger the change of state of the relay contact which is trying to tell the operator there is an issue with the system which may prevent proper detection of a fire (and/or a hazardous gas leak) and should be dealt with quickly.

Some units have this alarm as a Start-Check permissive--meaning the unit cannot be started until the problem is resolved. And, this is the usual cause of anxiety for operators, and technicians--who have ignored the alarm until the unit is ready to be started, but can't be started because of the alarm which has been present for some time (usually hours or days). And, the fire/FG system is one that should be visually checked prior to any unit START by a knowledgeable, competent individual to ensure it is ready for its task(s). Clearing any alarms on the fire/F&G system will most likely result in the removal of the associated anxiety.

Best of luck. Please write back to let us know if the anxiety has been removed, and how it was removed.
Very little information was provided, and most times when an alarm is described as an "anxiety" it's because it's preventing a START. So, in the absence of any other information, the most common reason for an anxiety-causing alarm was used as one explanation.

But, still, no information about the unit's fire/F&G system, or the Mark*....

And, the alarm logic listed is nonetheless a possibly very serious alarm--if the fire/F&G system is incapable of operating properly and cannot protect the unit and/or the people operating it.

This alarm condition is not usually a shutdown or a trip, but, some packagers of GE-design heavy duty gas turbines do sometimes use it to initiate a shutdown, or a trip as well as a start-check permissive. Without being able to the configuration and programming running in the Mark* at your site, it's impossible to say. It could just be a Process Alarm. But, if the unit continued to operate the last time the alarm was annunciated (when it was raining so hard), then it's probably not a shutdown or a trip--but it might be a Start-Check permissive. (You should be able to look at the Trip Display and the Start-Check displays on the HMI to see if the alarm is listed.)

BUT, the fact remains--it most likely indicates a problem with the fire/F&G system that could impact the system's ability to detect a fire or a leak of a hazardous gas, and it might also prevent the system from being able to discharge the fire extinguishing agent if a fire were to be detected. So, best to find and read the manual provided with the fire/F&G system to determine what conditions (because it's VERY likely that one or more of several conditions can cause this alarm) will result in this alarm.