ISO 13485 nonconformity

I wonder if you can answer a question for me.  My company is a custom manufacturing company that does not make its own product.  We help our customers in the design of their product and also build product for them.  We are ISO 9001 & 13485 certified. 

We have no change agreements in place with many of our medical device customers that clearly state if there is a change to process, documentation, components, tooling/equipment, etc. …we are required to notify them to (depending on the customer) make them aware or gain approval.  We also have medical customers where there is no such agreement.  One of these companies was recently purchased by a larger medical device company who provided notice that within a number of months, my company will be under a no change agreement, which we signed but is not applicable until July 2020. 

A supplier audit was conducted by this larger medical device company at my company’s site this past March, in the audit results there is a finding for an internal change order that did not effect form, fit or function of the assembly and keeping in mind there is not a “no change agreement,” yet the auditor considered this a noncompliance. 

I have perused ISO 1385:2016 and cannot find anything that would support this finding.  All of our procedures are in accordance with both 9001 & 13485.  Would you consider this a finding and if so, can you explain why?  I’m only looking to understand the perspective of the finding where there is not a “no change agreement” and we did not change material and the change did not affect form, fit or function of the assembly.