I agree...there can be alot of flammable items that a stylist would be carting around with. Nail polish remover; the powders for acrylic nails; polish; hair gel; hair spray, etc.
And if she threw her smocks in her car...well, fuel.
I wondered too about a reaction with other chemicals. But considering the large array of reactive chemicals that are normally present at a hair/beauty salon, I’d think if this sort of accidental cross-contact with hydrogen peroxide could produce such a highly flammable compound (or explode upon mixing) that there would already be a long list of examples of past incidents.