I've seen this occasionally. I think it happens if you don't press the eject button *all the way in* when you eject the card. If you don't press the button all the way in to eject the card, when you put the card back in, the button pops back up so that when you close the door, it pushes the button again.
If you *do* press the eject button all the way in, it doesn't pop up when you replace the card and all is happy.
That's what I see on mine at least.