I've had the same problem on a 97 Civic and am now having it on a 2000 Accord EX. Both were 4cly models and both had a mild ticking sound when it was cold. The sound would go away as soon as the engine made it up to operating temp. However, I didn't start noticing this until the engines started approaching 100K miles. Had the valves adjusted on both and no change. Tried additives, tried cleaners (thought I had a clogged oil jet). No luck. Best bet always seemed to just let it warm up before driving on cold days.