Oil filter bypass?

Hey guys. Don't post much on here, but I lurk quite often and now have a question.

I'm the original owner of an '09 Sport TuRD with the 1GR motor, obviously. I've got just over 66,000 miles on it and have been doing my own oil changes and general maintainence on it since day 1. The truck has been on Mobil 1 5W-30 since the first change and gets a new filter and fresh slippery stuff about every 5k miles.

So This past weekend I was due and drained the oil as usual. Looked fine for 5k miles (dark, semi-translucent color). Well, I spin off the Purolator Pure One oil filter I had on there and it was bone dry. And I mean dry like it just came off the shelf. No discolored oil on the filter and none in it. When I shook it, nothing.

Now, I always Pre-fill the new filter to get the element wet, write the date, oil type, and mileage right on the filter, and screw it down hand-tight plus 3/4 turn. But apparently the motor has been running on bypass since the last change. Anyone have any thoughts as to what the issue might be? No warnings lights, nothing to indicate it in this condition.

I chalked it up to a freak occurrence, finished my change, and started the motor. While running, I tried unscrewing the new filter and got the expected resistance from it being pressurized. Stopped the motor, cracked the filter more, and got plenty of oil out of it like I should. I have never heard of this happening before and searched here to see. I'm not freaking out about it or anything, but I would like to hear some possible causes. Air bubble in the filter air locked it and activated the bypass? Only thing I can figure. If the filter was bad, I wouldn't expect it to cause a blockage like that, but it's a first for me.

Thanks in advance for any possible thoughts on it.