All of a sudden I've noticed extra black (Dark colored) RWY's at quite a few Default FSX Airports with big Yellow "X"'s at either end (indicating RWY is closed).

 

Funny thing is that I've never noticed this before and do not recall vanilla FSX to have these?

 

Does anyone else get this and is there a possible add on that added this?

 

What is this exactly; a Bug or Feature or an indication that the RWY's have changed from the default that FSX installed???

 

 

 

I see that quite often with default FSX scenery.  I've even landed on them. 

 

Hook

I think that's a normal default feature, as you said to indicate RWYs that were not in service the time FSX was released - some of tehm may have entered service since, some others may have even vanished in real world!

And I have also performed a few landings on such runways - such a cool thing to feel like a criminal

An "X" on a runway or taxiway indicates the runway or taxiway is closed and is not to be used.  I presume some stock FSX airports feature such things if they were present when FSX was being created.