Uppercase domain

[ecchi]

My stats program takes referrer details from $ENV{'HTTP_REFERER'} trims off the http://www. and anything after the / and saves what is left (i.e. the domain name). Although it trims it, it saves it exactly from $ENV{'HTTP_REFERER'}. So can anyone tell me why my early morning stats included this gem:

torture-annie-in-bondage.com - 19
google.com - 3
google.com.mx - 1
greenguysboard.com - 3
google.co.in - 4
google.it - 1
TORTURE-ANNIE-IN-BONDAGE.COM - 1

As you can see it got the 19 hits from torture-annie-in-bondage.com but also one from TORTURE-ANNIE-IN-BONDAGE.COM. How the heck did it get a domain name in all capitals? Even if it was a type in, I thought the surfer's browser would have changed it to lowercase before sending it to the domain name lookup thingy ("thingy" being the correct technical term for any part of the Internet that I don't understand).

Any ideas?