I don't know if it has been like this, or only since the title bar got locked to the top of the screen, but, on my mobile devices, I browse using the desktop site. The switch to mobile site banner comes up every page load. I click the X, it goes away, choose a new page, switch to mobile banner is back.
That is kind of annoying. I can understand having it there once per site visit session, but, every page load is crazy. Should the site remember our selection to close it?