Unpleasant engine noise on start-up, 07 2.3 114000 km

[Roofrack]

First start-up of the day, had a really bad engine noise. clicking /rattling , really unpleasant sound, went away in about 2-3 seconds. Oil level full up, about 4000km on current oil(Pennzoil Platinum). Anyone experienced same thing, or have ideas on what might have been the problem, and is it going to become a problem. No noise last 4 days. Thanks

[pwdunmore]

I would think its from the VVT chain(might be getting slack in the chain so it may rattle against the cover), but if the sound went away it's kinda weird.

[Roofrack]

It sounded like maybe part of the engine was starved for oil for a second or two, then quieted when oil reached it. Don't know why that would happen, hope it's not serious.