If it goes away as it warms up, then tappets may be the issue. They should get checked every 24,000 miles but from what I have read, seldom need attention. As the engine warms up the clearances reduce, as does the rattle.
Someone else mentioned piston slap, but that only happens, in my experience, with old worn engines. Modern engines last for ever, compared to the engines of old, and I would be extremely surprised if a modern Honda (or any other manufacturer's) engine showed signs of piston slap after only 80K miles.