$750 for an inspection and permit?

I own a home in Houston Texas, and our tenants moved out in Nov. We have a property management company and they told us our house has a yellow tag on the gas line. They’ve apparently sent out a plumber who said that the line was tagged by center point because the cap was put on wrong or something and that they need to do an inspection and get a permit to get it off. $750!! Just to do this.

Does that sound right? Am I getting taken advantage of? That seems absurd just to fix a cap issue. And apparently that’s just for the inspection and permit, not even for whatever repair he might have to do (if any)

Do yellow tags ALWAYS need inspections and permits? What’s the best way to get around this? I need to do something soon because the new tenants need to move in.