This is normal. I've seen the same thing.

I am in Pittsburgh. The range offered for a senior level DBA is probably a 50k spread from the highest to the lowest salary.

The one constant I have seen is when a company is offering more than the going rate it's usually due to the fact that they have been "burned". Either they had good folks who left for better wages, or, they simply have had a series of impostors that were willing to work for a lower wage.

Good luck in your search.