WIN Server 2003 R2 became Win Server 2003 SP1

I configured some windows server 2003 r2. They are still running great. Just few days ago i checked my computer/properties and saw they automatically became windows server 2003 sp1. I did not do any updates they were installed directly from cd.
Now the question is do I install sp2 for win server 2003? I want to manually update them.

Thanks.