Ok you've worn me down - I hope Soundcloud is trusted enough!
(it's just as well we have some brave people in the world that are able to help transform an untrusted site into a trusted site ;^)
https://soundcloud.com/sullivang/ls3-cold-start-rattle
Ron - thanks for the links. I'd actually already read through those, but I'm not sure whether or not it's exactly the same issue as mine. What do you think?
One performance shop has listened to the recording and they're not sure - they think it's possible it's normal. (this is a different place that actually did the work)