Clattering valves

Well, it got up to 50 degrees Sunday so I thought I would fire up my 1300 and take her out for a short spin. When I started it up, the valves clattered for a long while but eventually got quieter as several minutes went by at idle. Is that normal? It seemed excessively loud clattering and a little concerning. After a warm up, I went for a 5 mile ride and bike seemed OK. Just wondering if any other member here has similar results.

motodan