The Bruins issued a release during the second period of tonight's game that Jonas Gustavsson has been taken to Mass General "due to illness."
Not to speculate AT ALL, because I sincerely hope it has nothing to do with this, but Gustavsson has had three heart surgeries in the past - one in 2011, and two in 2009.
Here's a post done by PPP a few years ago about Goose's condition.
According to the Bruins' PR staff, he has only been brought to Mass General for observation.