TempDb is used for several things in SQL Server. DBCC CHECKDBs, temp tables, row versioning, etc. If TempDb keeps getting to 2GB in size I would say that is a good indicator of the size it needs to be in order to handle all of the temporary objects that is being requested of it on a routine basis.

I would recommend changing the default size of TempDb from 1MB to 2GB to prevent the growth actions after SQL Server is restarted.