So, I had a bit of an issue today... But I suppose I'd better start from the front.

So, I unlocked my car to go to work this morning, started it up, let it run for about 10 seconds, put it into 'D', pulled into my neighbors driveway to turn around, but it into 'R' backed out, put it back into drive, and drove myself to work. Well, as I usually do, I stopped off at my favorite coffee stand. And like usual, I put it into park, and shut it off.

I then got my coffee, and started my car, go to put it into drive, and with my luck, it won't come out of park and into gear... So, what I ended up doing was using a tire pressure gauge to manually trip the transmission to get it into gear. Which worked fine. I drive the next mile, pull into my work parking lot, park, put the car in park, and try it again. Same thing... I didn't have time to deal with it. All the windows and whatnot work just fine. But when I went to use the fob to lock the car, nothing happened. I go to use the key to do it in the drivers door to do global locking, and only the drivers door locked.

What the hell is going on?!
Is this simply a battery issue?
Or is there something more serious at fault to worry about?

The battery could be the problem, but the inability to get out of park is often the brake switch. With the ignition on step on the brake and listen for a click in the shift mechanism. If no click it's probably the brake switch, otherwise maybe adjustment of the shift cable or micro switches.

Okay, so I know the click you're talking about. I noticed it the other day. When I kept hearing that the other day, I got a little worried, I didn't think it was supposed to do that. But I haven't been hearing it lately that I can think of... Haven't really been paying attention.

I just did a battery test, 767 cold cranking amps, battery charge 100%
the machine said "BATTERY GOOD"

I tried it again about an hour ago, and it worked just fine when I moved it out of gear. But what I don't get is why the key fob wouldn't work when I parked it at work today. The windows rolled up fine when I was in the car.
Now everything is working just fine... I have no clue what happened.

I didn't offer a comment on the fob because it's one of those things to be ignored unless it recurs. My XJ6 door locks do some odd things every few days and I just consider them symptoms of an aging vehicle.