Miter Box out of true

I purchased the Pro Miter Box from Lee Valley in July, and have been very pleased with it. Last week I needed to take the guide rod uprights out for safety (I was moving the shop), and once they were back in place the saw consistently cuts with a bevel, cutting from right to left as it goes down.

I have looked over the wells the rods sit in, and the rods themselves; neither has any scratching or bending that I can see.

There aren’t any documents for the care and feeding of the tool. There are no parts but the blade that can be replaced.

Could the blade be warped? It doesn’t have any visible defects, but it wouldn’t take much.

Is there something I can do to bring the tool back into true?

-- http://www.etsy.com/shop/Ossian