Good catch, I'm glad someone is watching out for us!
Since the topic (spray bedliners) came up again. I'll pitch my worthless opinion....
I had spray in bedliner in my Tundra. It was probably done when it was new. I absolutely hated it!!
First, it stunk.. bad smell even after 3 or 4 years. If I DID want sleep in the bed with the camper shell, I would not be able to stand the stink.
Secondly, the stuff is slick and anything you put in the bed slides all over. I had to put tie-downs and bungies on anything I wanted to carry in the bed.
Thirdly, my truck had a short shell top, so the sun here in AZ didn't get to it, but I've seen truck beds that are exposed the sun, and after a year or so the black crap starts to powder. It looks like crap! When the sun beats down it, it get hot, and acts like a "heat sink", heating up the whole truck.
And four... I've owned 4 Toyota trucks and a Chevy longbed, why do I want to protect the bed... it's a truck! In my 1985 Toyota shortbed, I hauled just about everything one could haul that would scatch or dent it. Everything from 700 rocks to scratchy pavers. And, yes the bed was a scratched and dented a little bit but it still looked OK.
I would guess that if there is any rust in the bed before you spray on the crap, you just cover it up and it continues to rust away and you don't see the damage.
That's just my worthless opinion.