I have just got my first uppy-downy seatpost (a reverb on my new Canyon Spectral 29er)
There is a small amount of play, the saddle can rotate a fraction of a degree from side to side. Is this normal or do I have a lemon?
Pretty sure its normal 🙂
If you stand next to the bike and shake the saddle, some play is discernible - this is normal I think. But you can't feel it when you get on and ride (in my experience).
Mine was rock solid when new and even after a years use it's got some lateral play in the top bush, which is a normal wear mechanism. But still zero rotational play.
My Reverb has a small amount of movement if you wobble the seat but you can not feel any wobble or rotation when riding...
I wouldn't worry just get out and ride your new bike...