on occasion, on startup i hear a quick grinding and then clunk. Fine after.

What is your question?

I'm wondering if some kind of solenoid could be leaking down and disengaging some component until startup. It sounds like a gear grinding until it reingages with a clunk. Very quick, within 5 seconds of startup.

What makes this problem better or worse?

only on startup after sitting overnight.

How long has your 2008 Honda Ridgeline had this problem?

only owned it for a month.