new sights question

[mhardy]

i recently had new sights installed on my glock 21. when i got it home and was checking them out i noticed 2 u shaped markings on the rear sights. Is this from installation? And is it common or did I get a not so professional install? Also i was told that I would need to "zero" the sights myself at the range. Does this sound right or do i need to find a new gunsmith? Any insight would be helpful!