Expires header - will it hurt me?

is there a problem if the date is in the past

[hyperion]

Hi,

I've got an application that is using sessions, realized with php and phplib. Now, I changed phplib so that non cookie-using visitors only get the sessionid appended to the url if they added something to the shopping-cart, so, for guys just looking around without buying, like googlebot, the site should appear as fully static.
The only problem I still have is that phplib sends a couple of "no-cache" http-headers for all pages, for example "Expires: Mon, 26 Jul 1997 05:00:00 GMT".
Will this hurt?

Regards,
hyperion

[Brett_Tabke]

Nope. (check the headers here...)