What Was That?

So the other day I went on a very long training run - all by myself. This was a victory in itself because I always run long runs with friends.  On this day, I just couldn't get my schedule to mesh with anyone else's.  The run went pretty good- the hamstring issue was not too bad and the pace was all right.  Do you get the feeling that it was a mediocre run?  Nothing special, but I am fine with that. Not every run is going to rock!!!  There was one strange thing that happened and left me wondering "What the ...?"  As I was heading into the parking lot (with .001 mile of 24 miles left!!) I felt a twinge in my right calf.  It really did just feel like a twinge so I thought "No big deal."  but as I took the next step I knew it WAS a big deal.  I could not step down!  What happened????  Can anyone answer that for me?  I hobbled back to my car and shed a couple of "poor me tears."  I sat down on the steps next to snowbank and immediately starting icing.  Then I walked up the stairs to the Y and every. step. hurt.  I made it to the Body Pump class and iced some more while I drank the protein smoothie my lovely daughter brought for me.  I have been icing and resting for two days and my calf is about 90% better.  I still don't know what happened and if I don't know what happened how can I prevent it from happening again? I need to know, I need to know more. Any ideas?  Ha ha - that sentence reminded me of this AT & T commercial. These commercials totally make me laugh - I am a teacher, I hear this all the time!!!
Commercial

Today we have a snow day!!  I spent the day baking and laughing with my oldest daughter.  Right now she is cleaning out another closet - she will do anything to avoid cleaning her room!!!!  I love snow days, but really waiting for spring weather!!!!