Receptacle Screw Connections
The plastic is highly insulated. Taking ABS as an example, the dielectric breakdown is in the range of 15kV/mm, meaning (in theory) that 10µm of ABS can separate 120VAC leads without risking conduction.

In short, it should not present a safety hazard. If you really feel it's necessary, you can bend that portion back up under the screw head, though.