Orchids are strange that way. Was one getting more light when you noticed the fragrance? Sometimes light has alot to do with how much fragrance an orchid will pump out. This past Sunday at my orchid society meeting, a lady brought in some orchids and she was talking about the overwhelming fragrance from one orchid and everyone was trying to 'smell' it, but it was gone. The air conditioning and lack of light in the room must have told it that it was not going to get pollinated there, so it turned off. lol.
You have beautiful blooms though. I especially like the white tip on the lower bloom. It gives it that extra something!