I suspect it's nothing to worry about. As others have said, the bilge pump won't get that last inch or so out. You may have had water condense on the walls and ceiling of the bilge, and after running the boat around, that water trailed down into the bottom of the bilge. The bilge is always a damp area, even in your driveway. My boat has a self-bailing deck. So any rain water is supposed to drain out the scuppers and not into the bilge. My boat's on a lift,so the bilge should always be dry. It's not, even with the plug out, there's often an inch of water in there (at the stern with the bow raised a bit) Water sneaks in there anyway, or condenses off the walls, or spray running through waves.
Your boat is sitting in water that's colder than the ambient air, so condensation will build up on the walls and ceiling of your bilge. Like a cold beer bottle on a hot day.
And of course during retrieval if there's ANY water in the bilge it will be tipped back to stern and kicked out by the pump. A quart or so is nothing.
If you're still worried and looking for a leak, while the boat's on your trailer stick a garden hose in the bilge and fill it up a foot or two. Then look for any leaks in your transom or bellows area coming from inside the boat to outside. I'll bet you find nothing.
I would not be concerned in the slightest about the amount of water you are talking about. Water that's colder than the air equals condensation in the bilge. I would consider a quart dispersed by the bilge pump, and a 1 inch strip of water at the deep V to be a dry bilge.
Of course frankthomas, it would help if it mentioned where you're from in your profile. If you're in Michigan, that's beercan-type condensation water. If you're in the Florida Keys, it's likely to be from the recent hurricane. Or if in Maryland, like me, it's the accumulation of seagull poop.