In 2009 NASA launched the Kepler (spacecraft) and promised that they would release collected data in June 2010. Later they decided to postpone release so that their scientists could look at it first.
Their rationale was that non-scientists might unintentionally misinterpret the data, and NASA scientists thought it would be preferable for them to be familiar with the data in advance so that they could report on it with their level of accuracy.
# See also - Open Science - For open science - Against open science