D'OH! I think you're right. I recently took the tires off, squirted sealant into the tubes, and put them back on, I must have put the rear on backwards, I'm pretty sure I would have noticed looking down if the front were like that. I was planning to swap front/rear this week anyways (and take the opportunity to inspect the tube in this trauma area), so I will make sure to put it back the right way!