IPhone :: Shuffle In Playlists Isn't Random

I have only had my Iphone for about 6 months now. It does some things very well.. others not so much. Here is one that I just cant figure out.

I have 80 or so songs in my Gym playlist, from about 70 different artists. (so maybe 3 blue rodeo, 2 Led Zep, 3 VanH etc etc)

When i go into the playlist and hit shuffle it starts playing and seems random but very often will play 2 blue rodeo tunes in a row.

When I say often, I listen to this playlist twice a week at the gym and it happens every time usually in less than an hour.

It is "shuffle" but my phone thinks it knows what I want better than I do? I DONT want to listen to two zep songs in a row.

I have checked the order on my playlist and it seems random enough to me..

Info:
iPhone 4S, iOS 5.0.1