Drifting to the right

I just bought my truck on tuesday and I have noticed that my truck is drifting to the right pretty good and it is really getting on my nerves. There is no unusual tire wear at all. It will hold straight for about 2 seconds the Wooop there she goes to the right. Does it sound like allignment stuff or is there something else I can check and do myself. The tires were just rotated as well as new brakes/rotors 15k miles ago

 

^That

 

Definately

 

I had the same problem with mine, and after talking with the front end shop it seems to be a common problem.
Like everyone said before have the alignment checked, but take it to a shop you trust and one that will listen. Just because the computer says the wheels in line does not mean it will drive straight. Make who ever aligns it drive it with you and don't leave until they get it right, it took about 3 trips down the road with the mechanic before we got it right. and by right i mean driving straight