Does the steering wheel supposed to be evenly centered when driving or is it normal for it to be a little bit to the left or right.

I did a 4 wheel alignment because the car was pulling to the left a little and now it's pulling to the right a little. The service manager said a little drift to the right is normal for safety reasons; would this be true?

But back to the steering wheel, it is now not centered when driving.

 

I would take it back and have them perform the service again. The steering wheel should be centered and the car should not pull in either direction. One caveat is that if you are driving on some roads with a "crown" the car will seem to want to drift to the right; however, this is a function of gravity and it should not "pull" to the right. Try it out on a flat parking lot where it should track straight ahead.

 

I agree with JRB.
One other thing: A year or so ago it was a common problem with RX's pulling left or right caused by Goodyear Integrity tires. It may be worth it to swap some tires around and see if the symptoms change. For more info do some searches here and on Edmunds.