I hope that is all I need. Drove to Seattle this weekend and noticed that in 5th under acceleration I would get a fair ammount of steering wheel shake. I just rotated my tires and never had this problem. So I'm thinking...or hoping that it is one of the less expensive options...ie. wheel balance or alignment.
Probably not...

Why would it occur under acceleration in 5th and not at any other time? (at least not as noticable in other gears)
1-3 is fine can't tell
4th...a little bit
5th...oh yeah..there it is.