Auxiliary cooling fan impending failure?

[Bottomfeeder]

Recently had the opportunity to take my black 2005 X5 E53 3.0 on a little road trip from Central Texas to Charlotte, North Carolina and back (a solid 2500 miles). The car ran great, no problems at all.

A few times during the trip (and since we've been back) I've noticed that the auxiliary cooling fan is LOUD intermittently, much louder than normal. It comes and goes, and seems to be most noticeable when I first start the car, or occasionally when I'm sitting in traffic.

I'm wondering if this is a common failure mode for these fans and if I should replace pre-emptively. I replaced the one on my other X5 (2002 3.0) a couple of summers back, and when it failed it just stopped working altogether.

Any of y'all experience loudness before failure?

Best regards,
Chris
Lockhart, Texas