I’m puzzled as to why there was any startle factor. The METARS prior to and during this arrival would have alerted me to the possibility of Windshear on approach (maybe even the ATIS stated it). I would have been self briefing (revising the QRH memory items) and later formally briefing the actions I/we would take in the event of a Windshear on final approach. Threat, error, management (TEM).