SQL Query Plan BUG

Hi all I am looking at the Query plan of a store proc. I found a very strange situation:

There is an index seek of a table which DOES NOT query inside the SP..how does it happen~?
i search around the SP , no where I can find a word related to that table. (Actually the table and index is really there inside the database!!!! )

I am using SQL 2008 R2 SP2, Standard version.Help.