perhaps send in this question to businesshalacha.com and see what they say. It might even make their popular newsletter “Business Weekly”.
I think the correct halacha it to ask a few photographres what standard business practice is. If standard practice allows for such a break than you actions were certainly warratned from a halachic point of view as all agreements unless specifcially mentioned otherwise are assumed to be subject to standard pracrtice for that field. if a hired photograohere would be expected to not take such a break then the break was in all likley unwarratned.
i would posit that such a break is likely expeceted and assumed by employers of photographers.
Kol Hahavood for looking to do the right thing in monetarty issues.