Google's cache of Custom 404 Page is showing my home page.

[internetheaven]

People don't always link right to my site, and bad inbounds always reach the custom 404 page which returns a 404 header.

But, I've been getting some strange info in my logs so I asked Google to view the cache of a page that someone was linking to incorrectly

e.g. http://www.example.com/mispeltfilename.html

and it is showing my home page as the cached version. If I go directly to that URl it puts out the correct 404 header and shows the 404 custom page.

Is this Google's bug or mine?
Thanks
Mike

[tedster]

We have another recent report around here of some flakey handing of a 404 page. If you use the cache operator and ask Google for cache:www.example.com/mispeltfilename.html, does the url change in the result and just show the domain root instead of the url you asked for?