I just discovered something about the shuffle.
Normally, when I shuffle my main library of 'Songs' I just hit the big green shuffle tab at the top.
Today......twice now I tried it.....I didn't hit the green shuffle tab.....I just started with a random song and started the shuffle from there. Both times it shuffled like how I think it's supposed to.....it is only playing songs that I haven't played in I don't know how long.
I hope this isn't just a coincidence. It's amazing how many cool songs I forgot that I saved.