Weird Tire Issue

Decided I was going to mow the grass one last time on Saturday. I mowed the area out by the road and then one pass around the outside of the yard. Was listening to the radio on my Pelter Worktunes, but the radio station started broadcasting a High Volleyball game. I don't think so, so I decided to run in and get my Microsoft Zune. Came back out and there was water (windshield washer fluid in reality) running down the driveway. Water was leaking around the rim, figure I had punctured it and was just losing seal. Did a quick once over but didn't see anything. Had Monica come out and drive the tractor so I could watch the tire. Still didn't see anything. Not wanting to lose the bead, I had heard drive the tractor to the barn while I rounded up the air hose. Put air in the tire and sealed the bead, but noticed the valve core was bubbling. I then went and got my collection of caps & cores (Daddy used to be a tire man) and my valve core remover. Removed it so I could see what kind it was, but put it back in real quick. When I tightened it back down, it quit leaking, but ended up swapping a new one in its place. I actually think the core worked its way loose. Not quite sure or how, but all seems to be well now. I finished mowing and then used the tractor yesterday. Haven't seen anymore fluid. Now at some point, I probably need to pick up a gallon or two and put it back in. Between this and a couple of years ago I ran a piece of wire through the sidewall, I've lost a little bit of fluid. Not a lot, but probably a gallon or two. Just kind of weird.

BTW, yesterday I took the deck off the tractor and powerwashed it. Painted most of the top and the underside. Noticed it looks like I've hit something with one of the shields and broke a weld. Need to take it to a buddy of mine and have him weld it back before I mow again. So far no damage, glad I power washed it, otherwise it was so covered in grass you couldn't see it.