If you look at the labels tab in the source control history in Visual Studio 2012 you could be confused by the changeset numbers. How can all the labels added by my different builds, done over many days, be associated with the same changeset?
If you look at the same view in VS 2010 the problem is not so obvious, but that is basically due to the column not being shown.
The answer is that the value shown in the first screen shot is for the root element associated with the label. If you drill into the label you can see all the labelled folders and files with their changeset values when the label was created
So it is just that the initial screen is confusing drilling in makes it all clearer.