Yep, needs to be reproduced to fix it. The good news is if it's a defect, it'll eventually gets worse, so be patient. Now, my guess is fan is probably hitting a piece of 'flashing' on the housing, which is excess plastic from the injection molding process. This has been the case in 2 other cars I had before, meaning noise WILL NOT get worse. Since you seem to be the DIY type, I'd go back and run your fingers all around where the fan could hit and feel for anything that could be hitting the fan. Also feel the blades to make sure there's no flashing there either. And finally, if filter is close enough to the fan, it could be a protrusion (or even flashing from the housing, but haven't seen it myself) on the filter or filter housing, so check everything. If noise is that subdued, sounds like what I described. Again, if it's the motor itself, it'll definitely deteriorate over time, so just wait until it makes enough noise all the time to make it obvious to a tech it's not normal. Hopefully that won't be the issue, but should be a relatively easy fix if car was designed well :grin:. Good luck, and keep us posted.