Like the message in the notification states, you're seeing that update because you've likely got some other component that released along with LabVIEW RT 2012 - NI-RIO 12.0, WSN 1.4, or Fieldpoint 6.0.11. The issue was to fix a specific problem in LabVIEW 2012 that affected RT, so if you don't have LabVIEW 2012 installed then the patch will neither be harmful nor helpful to you; however, NI-RIO, WSN, and Fieldpoint installer framework files for RT had to be updated to be compatible with the LabVIEW changes (and thus you likely have a component installed that has an update available, even if LabVIEW 2012 itself is not installed).
-Danny
