LOL....
That happened to me when I was an SL newbie. Not only that, it happened again 6 months ago when for some reason I twisted the key and just waited there expecting the boot lid (trunk) to pop up. Of course it didn't and I was left rather embarrassed alongside my colleague who was waiting - once I remembered I have to push it too, I had to just start laughing and tell him quickly!!
Still making me chuckle now...
Glad to see it's not just me!