SQL Server has encountered 1 occurrence(s) of cachestore flush
I also saw this in my own environment along with a few other messages: 


  
  SQL Server has encountered 1 occurrence(s) of cachestore flush for
  the 'Bound Trees' cachestore (part of plan cache) due to some
  database maintenance or reconfigure operations.
  SQL Server has encountered 1 occurrence(s) of cachestore flush for
  the 'SQL Plans' cachestore (part of plan cache) due to some database
  maintenance or reconfigure operations.
  SQL Server has encountered 1 occurrence(s) of cachestore flush for
  the 'Object Plans' cachestore (part of plan cache) due to some
  database maintenance or reconfigure operations.
  


It turns out there were multiple databases with the AutoClose setting turned on. 

You can check your own database with this command: 

SELECT DATABASEPROPERTYEX('DatabaseName','IsAutoClose')


Once we turned the setting off, the messages went away and performance improved. For further reading as to why auto close is a bad idea: 


Worst Practice: Allowing AutoClose on SQL Server
SQL Server Best Practices: AutoClose should be off