Is my database uppgraded?

I have some database that is restored in SQL 2008. I'm pretty sure
that it's created in an earlier version of MSSQL but the one who
restored it (an other company) say's it's created in SQL 2008.

Is there a way to determine if a database on SQL 2008 is created in an
earlier SQL Server version? Compabilitylevel shows what it's set to at
the moment so that says nothing.