I started receiving a message of api.foursquare.com (or something similar) when getting to the initial screen of the Android Foursquare app. When trying to check in to a location, I would receive a message that indicated a problem with the network. I thought there were just problems on Foursquare's end, so thought nothing of it.
It happened again today, though. Knowing that others had checked in, I figured the first thing to try would be to uninstall Foursquare then reinstall it. After I logged back in, things were working fine again - no messages.