Sounds like the VANOS, mine had a bit of a rumble / rattle before it was replaced at 80k. It's probably a bit of wear to one of the many parts on it, most likely the splined shaft that sits in the hub on the exhaust side, they do have some play in them. Doesn't sound like anything to worry about to me though, the death rattle is much more obvious than that (where the hub tabs break off) though not always depending if both have broke or only one, but caveat...see last paragraph.
However the only real piece of mind you'll get is if you take it apart for a look. Not a massive job to be honest and can replace some parts while your in there. You'll probably notice a similar rattle sound when you turn on the engine from cold for just a second if your listening for it.
Genuinely though you'll not get an accurate diagnosis from listening and certainly not from an internet forum listening to it. If you're worried get it to a garage who know what they're doing with it and can put your mind at ease
However the only real piece of mind you'll get is if you take it apart for a look. Not a massive job to be honest and can replace some parts while your in there. You'll probably notice a similar rattle sound when you turn on the engine from cold for just a second if your listening for it.
Genuinely though you'll not get an accurate diagnosis from listening and certainly not from an internet forum listening to it. If you're worried get it to a garage who know what they're doing with it and can put your mind at ease
