Sig 229 Sight Question

I have a used Sig 229 40 S&W with nite sights. I am shooting low left, during a basic pistol class one of the coaches asked if he could check the sites he too hit low left. He checked the site the front site has a 6 on it and the rear has a 8 on it. The coach was not sure if it is normal. Is it? Also the rear site is driffed to the left, how would I go about fixing it? Thanks

Sig 229
Mossberg 590