I would yes definately get an alignment. However mine has a constant vibration in the steering wheel when you get up to about 80 that I can't seem to get rid of either. I have had the rims checked, new tires put on, and had it the alignment done and one shop and checked at another and they said it was perfect. I don't know whats left to check but it wasn't like that when I bought the car....good luck on finding your solution!
Pakisho - New clutch - these need to be checked for balance (even though the factory says they are) before install.
LKG - If you have done all that and still get vibrations, check all suspension pieces for loose nuts.
Another possibility is that maybe you have a tire that is "out of round".
It can sometimes be solved by repositioning the tire on the wheel, but usually requires a new tire.