No problem! Our system is designed to overlook one-off misses (not completing a PH for any reason does count as a "miss").
If you have more PHs coming up that you will not be able to make, be sure to remove them from your schedule asap (along with any upcoming reservations).
Read the Priority Hours section of the Tutor Guide for more information about our PH system.
Note: even though you can't tutor from your device, you can do pretty much everything else using your mobile browser (dropping Priority Hours, checking reservations, etc.)!