I've been checking the oil reading every time I get in the car since changing the oil on Saturday. I'd estimate that I checked it at least a dozen times. Today, I checked the oil level 5 times (every time I got in the car after it sat for a little while). The first four times, the quantity read full.
The fifth time, the oil finally read 1/2 between minimum and maximum.
I don't think I'll top it off for a while; I want to monitor this situation a bit closer. It looks like it's a faulty oil sensor.