How important are automatic 301s?

[absoauto]

Ocassionally the URL for a product on our website will change. The shopping cart does NOT automatically create a 301 for the old URL to the new one. So in WMT the old URL's will appear as Not Found errors (even though all links in the cart automatically update, so there are no broken links within the cart).

These issues always sort themselves out with some time, but still disconcerting. Is this a major issue? Thanks!

[RyanPurkey]

Are these URLs that are only accessible while using the shopping cart or the URLs that any visitor would find, regardless of interaction with the shopping cart? If it's the latter, it is a bit of a concern and you should probably find a way to prevent or amend those changes. If it's the former, it's doubtful that you'd want the search engines even crawling that aspect of your site, thus you could disallow that portion.

[absoauto]

Thanks Ryan,

They are URL's that we would like to have indexed, so any visitor could find them. They don't change often, but if a SKU for example changes, the cart automatically changes the URL to match the new SKU, but does not generate a 301. I'll look into this, thanks for the tip.