(The bit in the kit appears to be a P6, so I’m inclined to order a P5 and see what happens)
Me, too, and it’s plausible that this machine has been serviced by Apple in the past, replacing the screws as Jeff Suovanen suggests.
iFixit shipped a pentalobe bit with the kit, but it’s too large for the actual screws, so it looks like I now need to get another bit. But what size?
Jeff’s link is to a driver with a P5 bit, and that page links to a P2 screwdriver, but since I don’t know what size I actually need (and I don’t have a micrometer to hand) I’m reluctant to buy two on spec.