All the residue that was splattered around the circuit board from burning the epoxy off probably isn't being too kind to the laser optics, either.
If you haven't used a laser cutter before, there's a long list of materials that you're not supposed to work on. Usually because the fumes are toxic, corrosive, or otherwise damage the optics. On the other hand, it could just be a particulate mess that needs to be wiped off. Tough to tell without knowing what that black epoxy is made of.
That said, knowing that it's possible to deencapsulate an IC this way is pretty cool.