whine near 3000 rpm

[tff]

I've searched this forum and the web regarding the below, but haven't convinced myself that what I heard was normal or not. Having said that... here's my situation...

I test drove a 986 Boxster S today. The car was great, except I was bothered by a somewhat mechanical-sounding whine around 2800 to 3000 rpm (all gears, and in neutral) coming from the engine area (from inside the car, top up). I noticed it right away and frankly it was somewhat annoying (but only near that rpm).

I'd chalk this up to being 'normal', but I drove another similar Boxster S (twice) a couple weeks back and I was only impressed by the engine noises... I don't recall hearing anything like this on that car.

(For those that may have experiences with a 944, the sound is similar to that made by a balance belt shaft that is not correctly tensioned).

Any thoughts on whether what I experienced is normal? What could be causing it if not normal? I'm thinking that maybe variation in engine tolerances is contributing to differences in the two cars?...