The 800XC has a beep tone whenever the oil pressure is low. They all beep for a second or two after starting waiting for the pressure to come up. It's normal, but unsettling for those not accustomed to it.
Without the beep, most folks aren't looking for the light when starting and never notice. If the light goes out inside of 2 seconds (1 is even better) of starting, the engine is fine.