Wirelessly posted (iPhone 3G: Mozilla/5.0 (iPhone; CPU iPhone OS 9_2_1 like Mac OS X) AppleWebKit/601.1.46 (KHTML, like Gecko) Version/9.0 Mobile/13D15 Safari/601.1)
I'd estimate it's happening at least once a week over the last month or two. Never for more than a few hours if you log out and log back in. Not that big in the grand scheme of things, but shoddy nonetheless.