I would at least be a bit suspicious. You can't prove or disprove virus infection without testing. If you don't want to go that route, keep isolated from other plants.
Bud's suggestion could be right. Pursuing the fungus possibility, go to the St. Augustine Orchid Society website. Read up on diseases, especially fungus diseases and look at their table listing fungicides. Pick a chemical that fits the fungus you think you may have, follow the instructions and treat the plant. If it recovers, you may have your answer.
A word of caution. If it blooms and the flowers are malformed or colors are blotchy - well, that could be 'color break', suggesting virus (again), and I'd discard the plant.