Cookie persistence expiration problem

Hi,

I'm getting a little confused when it comes to cookie persistence feature. I've set-up a lab instance of BIG-IP 11.3 VE along with 3 basic HTTP servers. I've put the servers in a pool and set-up a round robin load-balancing method. I've applied the default http profile to the virtual server and my own cookie persistence profile with a setting of "cookie insert" and expiration of 1 minute.

What I was expecting to see is once I make an initial connection to the virtual server IP a load-balancing decision would be made and, from now on, for the next 1 minute I will be redirected to the same server wit heach subsequent request.

What I'm seeing instead is different behavior on different browsers, none of which is what I've expected to see. On Firefox/Chrome every time I refresh the website a different server is being chosen (through Wireshark I see that the BIG-IP sends a cookie but the browser doesn't send it back with another request). On IE on the other hand I see that with subsequent requests the server is retained, the browser sends the cookie back, but the expiration doesn't work and I get redirected to the same server all the time until I clear the cookies and close the browser.

Am I missing something?

Edit: it looks like for some reason the cookie expiration date is shifted 1 hour backwards... The browser receives the cookie with the expiration date set as one hour earlier... I have no clue why, since the time on the client that is requesting the website along with its timezone is exactly the same like in BIG-IP device...