What's this?

[Plays_with_Toys]

Ok, I have a wierd noise/feeling coming from my car. When I go to start it, no matter if its warm, cold, just was running the car, etc... when I start it, right when it starts up and I let off the key I get "knock!" and I can feel a small jolt through the car.

Am I just holding the key a split second too long? Could this be a sign of a worn or loose motor mount? What else could I look for?

[subbyrs]

I'd be checking the engine mounts first....