Black Patch?

I’ve just started modeling my face, and I noticed there was a dark patch shown below:



Is this normal? If not, how do I solve this?

Select all vertices and
Remove doubles (W / remove doubles)
Recalculate Normals (Ctrl+N)

Thanks!

Just a bit curious though, is there anything I did wrong while making the model that caused this?

No. It’s just that every polygon has a front and a back side. When modeling closed, solid shapes it’s quite easy for Blender to determine which is the outside of the mesh and which is the inside and to align the polygons accordingly.

But how to do so with a mesh like yours, which is open and more or less flat? This gives Blender with every added polygon a 50:50 chance to guess correctly where the front and the back of the mesh is. And sometimes Blender just guesses incorrectly. The artefacts you see happen when a front facing polygon (light grey) is directly connected to a back facing polygon (slightly darker grey in color). In these places the mesh literally turns inside out.

The Ctrl-N command forces Blender to re-evaluate the direction of the face normals based on the overall shape.