I often (as in very often) rotate meshes using “r” twice, which rotates the mesh based on your current view in 3D space.
So if I’m in front view and rotate a mesh (in object or edit mode) with ‘r’ x2 it should be rotating only around the x-axis. And that’s how it worked for me - until 2.71. Now it often looks like this:
As you can see, the left on has been rotated using ‘r’ x2 with the input 90, the right one has been rotated with ‘r’ x2 and ‘manual’ mouse movement. So I guess the weird rotation only happens when I’m actually typing in a value. I guess it’s not really a massive issues, but I’m not really sure what is going on or rather wrong in this case.