Forgot to say please try to reply ASAP as we are visiting Orange County (where CCs are sold) for Xmas and can pick them up in person on Dec 26 rather than having them shipped. Thanks!

Can you pop them in a *low* heat oven for a bit to see if the warmth can flatten them out?

Mine took a while to completely lose the bend. I couldn't move things into the cabinets for a week or so once the shelves were installed because the island still had to be constructed & the floors needed a final coat of finish. In the meantime, I set heavy cans - like large tomato cans - on each side to press them down.

They are just fine after moving into the kitchen a few weeks ago. So much so that I forgot how irksome I found that hump when I first put them in until your post reminded me. I'm really happy with them now.

Ditto what amck said.
Mine now lie perfectly flat, but there was some slight bowing initially.
They don't need to fit really tight against each side. Could you have fit them too tightly? So that the bowls you put in compress them, but they decompress when the bowls are removed and are again too long? You might try trimming a tiny bit, just a 1/16th of an inch or so, off one edge of one of them and see if that helps.