Product, Add to Cart, CanonicalURL Leads to Debug Message

[web.geek]

Wasn't sure on the title...

So I just finished updating my 1.4.0.8 base shop to SVN 4901 (I think, I got it Late Mon/Early Tue). Everything is awesome, EXCEPT: When I add to cart from a product page, I get:

[Debug] This page has moved
Please use the following URL instead: http://test.whitemountaincandy.com/category/id-product.html'>http://test.whitemountaincandy.com/category/id-product.html

Where category is the proper url-rewrite value for the category, id is the proper product id and product is the proper url-rewrite for the product.

The address displayed in the browser is the same, but it is missing the /category part. For example:

Browser Address Bar says:

http://test.whitemountaincandy.com/11-caramel-chocolate-pretzels.html'>http://test.whitemountaincandy.com/11-caramel-chocolate-pretzels.html

but the message says to use

http://test.whitemountaincandy.com/nuts-crunch/11-caramel-chocolate-pretzels.html

Any ideas where I went wrong or how to fix? Thanks

[web.geek]

OK. I feel a little silly. I had the PS_MODE_DEV set to TRUE, so the debug statement was displayed. Setting it to FALSE in the /config/defines.inc.php file got rid of the message.

It makes me wonder: this redirection must be happening every time. Is that intentional? Are there any concerns with performance? Is this just a feature of canonical URL? Is it an SEO thing?