I wrote a server application that listens to the userstream 24/7.
It’s coded in Java using Twitter4J libraries, that I keep updated very carefully.
In the last 2 days the Twitter4J “stream closed” exception (that indicates a stream stop in the API) came out more than 100 times.
From the API status page does not appear any kind of problem. It is still possible that there’s some kind of problem on Twitter-side?