FYI

The only reason I recommend to rebuild the database is that each revision and release of SQL Server sometimes uses a revised method of creating physical database objects depending on what was updated. The methods of accessing these objects are also sometimes revised. Using some of the backward compatibility methods to access older database structures can cause numerous issues. It is always recommended to rebuild the databases under the upgraded server.

Depending on the size and complexity of the database, this may be a simple way to eliminate potential problems and possibly improve performance of your database.