Jim,
You are correct in that a header may not be needed above that door. The reason being is that the rafters are supported by the two outside walls, not the wall with the door in it.
The only thing the header will support is that small wall above it. At this time it looks to be hanging from the rafter, not supported from below.
So long story short, a header probably should have been put in to support the wall above it. Shortcut taken by someone
Jeff Sudmeier
"It's not the quality of the tool being used, it's the skills of the craftsman using the tool that really matter. Unfortunately, I don't have high quality in either"