First up make sure WAAS is enabled:
Main Menu>Setup>System>GPS - Change this box to WAAS/EGNOS
I cant seem to find where it indicates WAAS (I don't think it works in Australia anyway), but if your GPS accuracy is under 5m I would be guessing that you have achieved a WAAS lock. But if all else fails read the manual
http://www8.garmin.com/manuals/GPSMAP62_OwnersManual.pdf