I've ridden plenty of bikes with a similar "problem", I'm pretty sure it's to do with how bike gearboxes work - they won't change gear unless the gears are moving. It might be worse on the GS due to the dry clutch, which won't drag as much when disengaged, thus not allowing the driven side of the gearbox to rotate slightly. This is why dipping the clutch allows the gear to be engaged.
Of the few things I could fault with my GS, this isn't really one of them.