Did you figure out CS by using the Child Support Guidelines Worksheet, with you as the custodial parent and him as the non-custodial parent?
If so, that's the maximum amount of support you will receive even if he never sees the children (unless your income disparity changes more than 20% from the original filing values).
Now, if you filled out two worksheets, one with each of you as the custodial parent and took the difference -- which is what you'd do if you had 50/50 joint physical custody -- then yes, you'd have a legitimate claim for a support order modification. But otherwise? I'd say no.