If you have been feeding it well,it may have cloned due to favorable conditions.But then they will also clone in poor conditions as a survival tactic.So its hard to say why they clone
BTW the size of an anemone isn't an indication of age.It does take time for one to get big,but depending on conditions,another of the same age may stay small it whole life.Or keep splitting like yours seems to be doing.Nice to have a splitter
