It looks like a smoothing issue–where it would be trying to smooth the front to the side. You have the option to set up smoothing in your 3D program before exporting to UE4 or it can try to generate the smoothing on import.
If it’s a lighting artifact, then most likely you have UV’s that are overlapping or those faces are too small in the UV’s, you can try increasing your lightmap resolution for that mesh or improve your UV’s.