Did you apply for Discover Business or Discover More? I have both.
At the time I applied, I simply asked that they take 5K of my 10K credit line on my Discover More card and open the business account. Since then I have asked for and received CLI's on Discover More of 3.5K. So, now I have one at 8.5K and one at 5K (they aren't considering CLI's on business accounts at this time.)
Hope this helps.
Starting Score: TU 737 EQ 721 Current Score: TU 741 EQ 741 Goal Score: TU 765 EQ 760