Not long after I got the Prius, there's a rattle in the console mounted into the head liner. If I press on it, the rattle shifts. Sounds like the wire that feeds power to the lights is probably smacking against the roof of the car. Anyone else experience this?
Sorry to hear your '13 has a rattle as I thought the new G3's were more rattle-free (Toyota must have taken a bunch of flack for the rattles in the '10s). It took me 3 years to find a subtle "ticking" sound in my headliner. At least for me, it turned out to be a large piece of rigid styrofoam that had come un-glued from the roof. It was abrading the metal roof making the sound. Out it came! No rattles since. I can only assume it was there primarily for the manufacturing process but doesn't seem to serve any purpose now. Do you have a sunroof?
You might ask if anyone here knows how to pop out the overhead light assembly so you can check behind it for something that could cause this noise. It could be a wire or maybe another piece of styrofoam that came loose above or next to it. Best of luck...chasing rattles down in a Prius is no easy job.