The airbag doesn't randomly go off. The issue is with moisture causing corrosion in the inflator casing which can rupture on airbag deployment, sending bits of shrapnel out inside the airbag. Currently only NZ new vehicles are being recalled, all gen 4s for Legacys. Unless you bought your car in the last couple of months, you'd know if it's been replaced or not - you would have had it in at your local dealer. So far my work has done 40 or so. Got them down to just over an hour, and yes, the dash comes out.
There's no point annoying your dealer about it. Unless you've had the letters from Subaru NZ, just sit in the queue like the rest of us.