I found the issue. A reference in the volume definition was causing the issue. Not sure what the symbol means exactly, but it was present in the volume sketch also. Once the reference was cleaned up the symbol went away.
It looks like the "packaged" icon you get when something isn't fully constrained. If you look at the pictures below you will see detail 502 has a single rectangle. This item is only partially constrained in its assembly. Below that you will see two features (SB1_S1 and SB1_S2) that have double rectangles. These are features in another model that reference the partially constrained detail (502). The double rectangles help you know that something that these features are referencing is not fully constrained. Tom