If you search youtube for a 737 landings compilation, you'll see that many 737s seem to touch down fairly lightly initially and then (I assume when the relevant weight on wheels, wheel spin up, throttle position requirements are met) the spoilers deploy, the aircraft sinks quite swiftly on it's main gear oleos.
I've always thought even the smoothest touchdown on a 737 seems, in the cabin, to feel like a bounce when it's actually not.