Engine Knocking

My mechanic called to my attention a knocking coming from my engine. It happens mainly at hot idle. It increases with RPMs. It seems to be coming from both cylinder banks, and is the loudest from the wheel wells. It sounds somewhat like someone knocking on a wooden door lightly. Anything i should look for?

-Mike

But it seems to have cured itself. I went down to check the oil, and i couldnt get it to do it again. <shrugs>

-Mike

[DavieGravy]

It's funny how alot of the problems people are posting, I'm currently experiencing. Does it do it while it's warming up, then go away? Mine does.
Dave.