Yes, that can definitely be an Euler angle problem like I was talking about. If you do a Quat slerp it should work.
Just as an example, Euler angles go from 0 to 360 Degrees (well really in Radians, but that's not important for the problem). So let us say the angle of the box is at 10 degrees and the angle of the camera is at 340 degrees. We know this is only really a 30 degree difference. But if you were to simply interpolate the value without taking the looping rotation into account, the box would then rotate 330 degrees (in the wrong direction), which is obviously not what you want.
There are ways to still work with Euler angles and get it to work (by checking for angles near the 0/360 boundary and doing some math) so you can try this if you want. But using Quaternions and slerp should be a cleaner solution, and also avoid other problems (like gimbal lock).
