Hey @sjp , this is Blender working correctly! It’s because those sides are now n-gons. I cover this a bit in the end of the video on loop cuts:
https://cgcookie.com/lesson/loop-cut-and-slide-02393710-1782-4224-97a2-86b0441cf114?wtime=308
For a more in-depth exploration, check out the Mesh Modeling Bootcamp for your next course:
https://cgcookie.com/course/mesh-modeling-bootcamp
Happy modeling!
