Ignore the file modification dates for SQL Server database files. They're not updated every single time a change is made to the DB, that would be useless overhead.
Gail Shaw
Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability
We walk in the dark places no others will enter
We stand on the bridge and no one may pass