we47b1me

Spotted a tiny piece of this, the rubber crumbled in my hand and was able to pull it back this far until it stopped coming. Slightly worried it might be rust... Car spent a few years in NY at the beginning of its life, but Florida and California all after that.

ygmn

Looks like rust to me under the undercoat.

Clean up and or apply rust eating primer then paint then undercoat again.
I would peal back until you see clean metal

billygoat33

Sure looks like rust. I ;ike Ospho, you can put it into a spray bottle and squirt it in any holes. Big thing with Ospho is don't contaminate it by dipping a brush into the bottle.