It is normal Fiat, as Barbara said, just the way it is sometimes. Typically I get mine to bloom in sequence first two opposites, then next two opposites. By the time the last two are in full bloom, the very first bloom is on its fade away. It takes a lot of energy for the plant to keep them all. Just enjoy the show which lasts about 2 weeks, that is how it goes with mine.
Your Samba is coming up soon, so your bloom show continues woohoo!