Bad Knee

I'm not a person who sits around much except while eating lunch and reading the newspaper or at dinner.  So movement is not usually a problem.

We had 8" of snow recently and I noticed no birds at the feeder.  Bad timing to run out of black oil sunflower seed in the feeder.  But this is exactly when my bird polulation needs a little help, so I went to pull on my boots to go outside...

And my right knee said "NO".  Really, I sat down to pull on a boot and my right knee suddenly went painful.  No hint before.  I managed to lift it into the boot top and put on the other.  Ans limped to the stairs.  The stairs were and adventure.  One step down  with the left foot and follow with the right.

I limped across the basement to the metal can I keep the 40 lbs of black oil sunflower seeds in and filled the bucket marked to how much the birdfeeder will hold.

I was dreading carrying the stepladder to the feeder.  It hurt to walk to the basement door.  I undid the security bar, and turned the doorlock...

And the knee was suddenly just fine again!  I carried the seed bucket out, carried the ladder to the feeder, and opened it.  I had a twinge climbing the ladder but just for a moment.  Filled the feeder, but away the ladder, brought the bucket inside, and hours later, no problems.

I wonder what causes that to happen?  It would make sense if the knee kept hurting or that if never did.  But what would make such a temporary problem?

Getting old is weird...