Caulking around aluminum clad windows?

The house we just bought has wood windows that were clad with aluminum to save the maintenance issues with wood.It has been on the windows for 20 yrs. It doesn't look like anyone has ever caulked around the outside fo them. From an energy standpoint, I think it should be done. But since this is NC I'm worried there might be a reason not to seal them. Can anybody answer this for me?