Credence was only a couple of hundred years of age compared to other angels, his age considered young meaning he wasnt trusted with prime tasks

Always trying to prove his loyalty to God and upper ranking angels, seeking approval

When he felt a creature like yourself lurking he did his best to find where you hid, wanting to find a demon and kill it to prove he was worthy to God

He was too weak to use any power to realise you were in plain sight, playing with the Angels weak mind