If that is loaded and at the bottom end of the stroke it looks … unexpected.
Colours are Von Mises ?
My experience with Calculix for elasto-plastic cases is not sufficient to tell what (not) to do.
I asked the professor at the university about that situation. He said:
This is normal and is observed in the real process, as the volumetric stress-strain pattern is already active on the edge, rather than the flat deformation as on the main width. The smaller the width of the workpiece, the more pronounced this effect is.
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This is the effect I was thinking of and the corresponding cross section. I was not aware that the line moment is strong enough to actually lift the workpiece off the tool. Learning something everyday 
. Thanks for sharing.
If you do a test bending, you can probably determine the width of the actual contact area and its distribution through the bend angle.
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Since the material is unconstrained at the edges, it can and will deform away from the top die so the material under compression isn’t compressed as much and remains closer to its original length.
Try plotting the signed von Mises (sgmises) stress.
That should show you the compression and tension more clearly.
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Anticlastic curvature.
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