Christopher,
Thanks for using the Events Calendar, let me try to give you a hint on how you can do this.
The tribe_is_past() function is set to “Returns true if the query is set for past events, false otherwise”
So it does not detect on a single event that it is in the past only in a loop.
You can use these two functions to get the start and end date of the single event:
tribe_get_end_date()
tribe_get_start_date()
You could then write a conditional statement to compare to the current time with the returned time from those functions.
You will have to format the time from those functions to be able to compare it to a function like php’s time()
It may take a couple tries to get the formatting synced up. Let us know if you would like any more hints.
Thanks!