Sounds like you need to replace either your inner or outer tie rod on the passenger side. They should've inspected everything when you got it aligned, and told you if you needed anything replaced or not.
Put the front of the car up on jackstands, and with the steering wheel locked grab each wheel and rock it from side to side (imagine that you're trying to make the wheel turn left or right). If there's any play at all in it, it's got a bad tie rod.