cried in the car on the way home, processing or panic?

so we left a hotel meet about 1am, everything had gone genuinely well, no drama, no pressure, even the goodbyes were warm. ten minutes into the drive home i just started silently crying. my husband saw and pulled over, asked me what happened. i couldn't answer because nothing had HAPPENED. he was lovely about it but i could see he was worried. by the time we got home i was laughing again. how do i know if those car tears were just emotional release vs my body telling me something was off? i hate not being able to explain it to him