If you have STD selected and then 'twist' the QNH knob (or barometric selector) in either direction, the preselected QNH (the white numbers) always starts from 1013.
Yep, I've seen this too. Pre-selected QNH starts from 1013 when you twist the knob with STD selected. At first you'd think it started from the previously set QNH, but it probably makes more sense to start from standard...origin and dest can be huge distances apart :-)