The launch service provider has the last say on the date of the launch. The customer provides orbital parameters, and the launch just needs to make sure that insertion happens. Delaying for weather is pretty common, and as long as the payload gets to where it's supposed to, everyone's happy. The Orbcomm contract wouldn't have had a launch date specified, except in terms of NET (no earlier than) or similar. The launch windows are decided by SpaceX based on the requirements, and are the other constraint, and there was a window on both days.