In the sample above, you are setting a "Set-Cookies" header, which isn't quite the same as a "Set-Cookie" header. The singular version is correct.

UPDATE: About the other idea being considered -- I was thinking, as growlf said, that the order of the headers shouldn't matter. I had a look through RFC2068 (the HTTP 1.1 specification) and, if the order matters, I surely can't find where that's defined.

(Of course, I'm assuming here that the standard is being followed, which isn't always a good idea.)

- Matt Riffle