I billed retainage on Feb 20th as we were officially completed with the project. The contractor asked if we could do additional work that was not included with our contract.I sent a notice of retainage out on March 27th as we were offsite on 3/17. The contractor said I have to re-invoice the retainage with the April 20th date. If I do that, will it mess up the Notice and lien rights?