Originally Posted by
YOJiMBO20
Sounds like the air just leaked out of the tube, but it wasn't a bad tube.
Put the old tube, while inflated, into some water and look for bubbles. You'll quickly find the puncture, if indeed there is one.
Indeed, I didn't do the water test. I ended up just tossing it, since it did deflate again after several hours. But I am curious--I might go yank it outta the trash and stick it in some water to see