GNU Emacs 24.5.1 (x86_64-apple-darwin14.3.0, Carbon Version 157 AppKit 1347.57) of 2015-06-01 on Singularity-2.local
Steps to reproduce:
1. Make a heading with some text underneath
2. M-Return to create a new heading
3. M-Right, M-Left would get you to the same heading level, but the cursor would be further to the right than started with.