Dual Extruder Second Head Bumping

Hello, can anyone with the dual extruder (Taz5) tell me how to avoid the second hot end bumping the model as it passes by the perimeter of the model? I have checked the front to back vertical alignment and it seems to be perfectly aligned, yet as it is printing with the first head the second head will bump the model edge and some other slightly higher points on the model. Do I need to worry about these bumps?

Thanks,
Mike

I found the Z Hop setting under expert/retraction. Set to .2mm and this helps a lot.