Permalinks, FireFox, and extra “GET” entries in apache access_log

I am using the /%category%/%postname%.html permalink structure on two WP sites and while tailing the apache access_logs see some very odd behavior. It appears that FF (?) is issuing an unnecessary “Get” request each time a user clicks on a post. Bear with me as I try to explain the scenario.

For this example
post 367 = /instructors/john-doe/bio.html
post 548 = /buildings/townhall/smith.html

1) A user clicks on a link that points to a post with a permalink structure of: /instructors/john-doe/bio.html

2) When I look in the apache access_log, I see
“GET /instructors/john-doe/bio.html HTTP/1.1” 200

but I also see at exactly the same time:

“GET /buildings/townhall/smith.html HTTP/1.1” 200
with the bio.html as the “referring” url in the access string.

Note that there is not even a link to smith.html on the bio.html page!

3) If I make the same request with Permalinks disabled, all I see in the access log is:
“GET /?p=367 HTTP/1.1” 200

which is what I would expect.

Hmmm … the only browser that appears to trigger this behavior is FF. I’ve tested with various incarnations of IE and Safari and I only get one correct GET entry in the access log (even with permalinks enabled).

At first I thought this might be cache related issue, but after disabling all plugins (and of course clearing all local cache files) this random extra GET request continues with FF when permalinks are enabled.

Any insight would be appreciated.