Strange noise after water impeeler replacement on Alpha One Gen 2

Hello,

I pulled my lower unit off last weekend and replaced my water pump impeller and replaced the drive oil in the lower unit. I had no problems with any of the work except that when I started the boat up afterwards, I noticed a "whirring" sound coming from the outdrive. My inital assumption was that the impeller needed to "wear in" and seat properly since this is the first time I've replaced the impeller. I took the boat out today and the noise is not going away. It's not an overpowering noise but is certainly noticeable when idling. I have no other problems and everything runs fine and I have no cooling problems. I plan to pull the lower unit back off tomorrow to see if I can see anything wrong. Anyone have any suggestions as to what I might have done wrong? Is it possible I put the plastic water tube back in incorreclty and it's rubbin on the shaft?

To try to head off some of the obvious questions, to my knowledge, the fins on the impeller are pointing in the correct direction and when relacing the drive oil, I pumped it up from the botton until it came out bubble free from the oveflow screw.

Any help would be greatly appreciated.

Thanks,
Glenn