Blender UV unwrap making too many islands I am trying to unwrap the UVs on this object and have marked the seems so there should be 4 islands, however once I click the "unwrap" button Blender seems to make several extra islands, some of which are only one face. I have checked to make sure there is no non-manifold geometry and there is none.

If it matters, I have been 3D modelling for a few years but have only recently picked up Blender. I am more used to unwrapping in Maya but would like to learn Blender. I have tried googling for this issue and have only found tutorials on UV unwrapping, none of which address this specific issue.

Attached is a picture of the model with transparency on so you can see the marked seems, and then a picture of the UVs made after clicking unwrap, I spread them out a bit just so you can see how many small ones there are.  

Thanks in advance.
It isn't that you have non-manifold geometry, it is that the UV seams "cut" the mesh into pieces.

You need to find the separated faces on the mesh and remove the seam from one of the edges so it stays connected.

With both the UV/Image editor and 3D view visible, enable the sync selection option so that the two editors use matching selections. Then Select the UV islands so you can see them on your model and clear some seams to keep them connected to the rest of the mesh.