Took advantage of the 30 minutes free today on MKE-MCI, but I never got a warning that my time was expiring. So when I clicked submit to post what I had been writing, no luck.

I had been on the same screen for awhile and perhaps you only get a warning when you send/receive information, say, starting at 25 minutes in. But I was just typing on a static page over the 30 minute mark (apparently) and got a rude surprise.