About a week or two ago I started getting this weird clunking sound when I turned my car off. Normally, I wouldn't worry about it, but it is very loud. It seems to happen maybe 1 out of 4 or 5 times that I drive home from work late at night, so the engine is probably only luke-warm. I might expect it to be metal expanding/contracting except for the fact that it's so loud. I've got just over 4k miles on my Z, so it's well past it's break-in period.

Anybody else have anything similar?