Mine went to a chiro, not osteo, but sometimes they were a little unsettled after a session - come to think of it, it was their first session that they would seem unsettled, but they would usually be much happier the day after. I found they reacted better after the next sessions - maybe the initial adjustment makes the most changes and that's why they are a bit out of sorts?
If your bub is still unsettled tomorrow, give the osteo a call and ask for their advice.
