Contractor charging extra for rough materials - is it legitimate?

We are mid project of a bathroom remodel, it is our first time doing any renovation so we are admittedly ignorant on how some things usually work. So far things have been going smoothly and our contractor just finished demo, plumbing, electrical, drywall. He just sent us a new invoice/change order for a little over $2000 for "materials". I asked for a breakdown and it includes what I think would be considered rough materials (drywall, tile mortar, 5 gallon buckets, PVC, an oscillating tool blade, etc).

Probably on us that we should have clarified but we assumed these kind of materials were included in the quote which I have reviewed and it doesn't specifically say if these items are or are not included. There is an exclusions section that lists things like structural repairs beyond visible conditions, hazardous materials remediation, and changes requested after work begins which all make sense to me, but I would think rough materials would be included in this exclusions list if it was not intended to be included as part of the original quote.

I told him this caught us off guard and was unexpected and he said he charges all his clients this and it's typical. Just want to get a third party opinion if this is the norm?