Front Cap Rust Stains

Following the door side of the front cap along the trim that's caulked I've developed a rust stain that follows the trim piece along the underside of the right side of the camp toe the hitch pin. Today (the last warm one for awhile or maybe the season) I'm going to remove the caulking and put new caulking. Hopefully that will make the difference. We are expecting rain so I want to caulk and clean up.
I remember some others having this problem and hope the chime in and offer some advise.

Exposed screw head on the roof or gutter trim bleeding down? Might even be one under a piece of loose trim.

Well today I pulled off all the caulking on the door side of the front cap and re-caulked it with ProFlex, it stays pretty flexible after it dries and should hold up. I also cleaned off the rust colored drip trail which ran under the front cap and down the hitch pin cover. It's suppose to rain again tomorrow so hopefully the rust colored trail won't appear.

Thought the caulking job did the trick, but no. We had a heavy rain and I didn't have a rust stain under the front cap and down the hitch pin cover so I thought I was all set but then today I checked it again and there was a faint line, not as dark as previously but still there. I can see this is going to be a long project. I am going to check screws and see if they are the culprit.