Toddler phase

I've noticed that anytime my son is crying with his dad, when I come into the room and ask what's wrong (nornal tone) he immediately stops crying. If hes crying dad during bedtime and I step in, hes calm and goes to sleep. Is this a sign of comfort or fear? Online im reading that children cry with the parent their most comfy with and he cries with me sometimes but seems to stop quickly when I check on them. My biggest fear is him feeling like he can't express his emotions safely and I've had moments of reaction during some meltdowns as im learning and I wonder if that caused him to feel a certain way.