Ahh, I am using the onelogin library on one of our other apps to sync and found I can send isPassive param though.
The problem with this is that the session id changes and another X hours are added to the timeout.
Is this normal?
<saml:AuthnStatement AuthnInstant="2015-08-20T16:34:09Z"
SessionNotOnOrAfter="2015-08-21T00:39:49Z"
SessionIndex="_XXXXXXXXXXXXXXXXXXXXX"
>