Typically, you have a grace period before you need to transfer insurance. For example, if you purchase a replacement vehicle most state laws and carrier guidelines automatically cover the vehicle for XX amount of days (0 to 30, depending on the state/company).

Therefore, you should be covered on one vehicle or the other as long as you were within the grace period. 

Insurance guidelines and state laws differ so you would need to check with your own insurance carrier to see at what time the insurance transfer became effective. They should be able to tell you if you were covered for the full day or only after the time in which you made the transfer, 9:30 am.