No, because when you attach a saved spec, it copies those specs into the design of the report. It does not monitor any future changes to the saved specs in the form. You could even delete the saved specs from the form, and the specs that were saved with the report would still be there.

In many cases, it's best to design reports with only an attached sort spec, not an attached retrieve spec. Then, use a saved retrieve spec in the form to get a 'result set' to run the report against. That way, you can always modify the saved retrieve spec that is attached to the form, and use that with the report in the future, without needing to redesign.