Thread Verification after paint

Hello, new to the forum and role of quality inspection. Wasn't sure where to post this in the forum, but looking for help\suggestions on this.

We manufacture a product for the process industry, this is a cast\machined aluminum housing that is pre-inspected before going back out for paint. The problem is (or is it a problem), the conduit entries (M20) are verified with GO gauges before going to paint, but when received back in, a GO gauge will not go in because of paint on the edge of the starter thread. A typical M20 plug, connector or conduit will thread in fine. The only reason we gauge is because another branch of our company in Asia Pacific is verifying with Go gauge, but it will meet the customer requirements when installed.

Question, is gauging required a second time if it meets customer requirements? Is this up to us to specify on our documentation?
Thanks in advance!