What happens if my ticket expires on the MAX?

Just kinda curious because I've been stopped by fare inspectors on the train a few times in the past few months.

Let's say I tap my card and hop on the MAX in Hillsboro, ride 45 minutes into Portland, spend 90 minutes in Portland, then get back on the MAX and ride back to Hillsboro. That leaves me 15 minutes on the MAX before my ticket would expire, and even if I tapped my card before getting on the train in Portland, I would not be charged again and my ticket would not convert into a daypass. What would happen then if I was stopped by a fare inspector 30 minutes into my return trip? Can they see that I got on the train while my ticket was still valid? Am I supposed to leave the MAX and tap my card again when it expires?