Commonsense: I remember learning about this in a psychology class. Even if a person overcame their feelings of shyness, inferiority, awkwardness, low self esteem, etc. and became a confident and self secure adult, they might still revert to their old feelings when meeting someone from their past whom they haven’t seen in a long time. It sounds weird but it does happen. It’s not uncommon. The mind works in strange ways.
So don’t worry. You’re perfectly normal.