Rattle After Startup

[LEXUS IS250 AWD]

Does anyone notice a rattling sound from under the hood after starting the car? It lasts just about 1 second. Used to happen once in a while, now it's a bit more frequent. Any idea what it could be?

[tex2670]

There's a TSB for it. But the dealer won't do the fix unless they can replicate it. I only get it about 1x every 6 months.

[bartkat]

This has been covered here including the TSB.