It has never actually been on the water yet, I just had a hot foot installed and that tech noticed the play in it. He pointed it out and said it did make any sense to him, but not being a Mercury rep and knowing its brand new he said to make sure before running it.
Got a chance to look around it, I think they installed the wrong rear thrust hub. The one that in it was the full length of the prop, but there was another one with a drive sleeve in the box of paperwork and such the dealer gave me that is half the length.