My DS 3.7 has been able to label emotions of eg characters in books for a while (before he turned 3 for sure, can't remember exactly when!), saying whether they are happy/sad/cross based on their expression.
He's recently (in the last month or so) started voluntarily telling us how he feels and why, eg "I'm sad mummy has gone out" or "I'm sad Nanny has gone home". This is quite new, he would have been able to answer "I'm happy/sad" when asked before, but he never would have voluntarily told us.
Is this on track for his age? I can't really find anything online...