Welcome to the Orchid Board! Those are beautiful flowers.
Cattleyas can have spots of darker color near petal tips. It doesn't look virused. The brown spot could have been a scratch or other mechanical damage. A fungus called Botrytis can cause numerous brown spots on orchid flowers in conditions of coolness with high humidity, but just one spot is not likely Botrytis.
__________________ May the bridges I've burned light my way.