Loop Cuts adding extra lines to make triangles.

My loop cuts, on two different projects now, are adding extra unnecessary lines at angles, creating triangles.

All my faces are 4 sided.

Anyone know why?

I can then go in and delete those edges and then I get exactly what I want. So the extra geometry wasn’t even necessary. So why was it automatically added in the first place?

In fact, the purple line is only on two faces of the four I am trying to add the line around. Once I LMB, though, is when the funky angles appear.

http://www.pasteall.org/blend/13501

Remove doubles and inside plane where arm starts.

Happy blending!

where the arm starts remove the face in there and remove the doubles after words and have fun blendering