Paul, sorry. I was off tutoring someone else in using SketchUp. Anyway, how did you create the component in the screen grab? The component axes weren't in the right place. I have some guess about why they are where they are in that shot but it probably doesn't matter. SO, if I had seen this before you deleted the component and redrew it, I'd have suggested changing the component's axes.
To do that, select the component so it has the blue bounding box visible. right click and choose Changes axes. Set the location of the origin at a corner of the component and then click to set the red followed by clicking to set the green. The blue takes care of itself.
Oddsocks probably was close on his diagnosis. It's possible there was a drawn line laying on the red axis or perhaps a hidden line (View>Hidden geometry) that was included inside the bounding box.
Even if the comoponent axes aren't on the component, you can tell if there's excess geometry by looking at the size of the blue bounding box.