I don't know why that line bugs me so much, but it always has. I get that she's basically excusing herself (+1 for politeness), but red alert already implies all officers should report to their duty stations immediately. It should have been a given.
The boring answer is that just like "shields up", it's there to help the audience. Maybe they did a take where she just hurries away and it looked weird so they added that line.
Or maybe she just really needed to go for a Commander Data, if you catch my drift.
Deflector systems are automatically brought to tactical configuration unless specifically overridden by the Tactical Officer. All available secondary and backup deflector generators are brought to hot standby.