User callout is shown all the time (once per session)

Affected version: 9.0.2 (omnibus)

After the Upgrade to GitLab 9.0, a banner ("Customize your experience" with a link to my profile settings) appeared on the first login. After dismissing it, it stays out of the way. Until I log out and in again or restart my browser, then it appears again.

What I would have expected is the banner to be displayed once for my information and then be gone for good. This is a bit annoying since it takes up quite some space each time I start a new browser session on our GitLab instance.

Technically, GitLab stores my dismissal in the cookie user_callout_dismissed. This is a session cookie, which explains the reappearance of the banner. Shouldn't this be stored in a more permanent cookie or in my preferences on the server?