Not in the checklist...While you're looking at the underside:
Bolt/Washer check:
Rear hard plastic "diffuser": Check for all attachment bolts - there are 5 visible bolts (3 (near aero cover) + 2 (mid cover) + 1 open hole (no bolt, mid cover)), plus 2 under covers (near the very back of the car). Make sure they are tight.
Mid Aero Cover (softer material under rear motor): Check for all 13 bolts (there is one right in the middle). Make sure they seem tight.
Front Aero Cover (under front motor): Not certain of the bolt count here - it's about 8 though. In particular make sure all the leading edge bolt/washer combos are present.
Just make sure they are all there. Not unusual for them to be missing or loose.