dried sandwich spread sealer?

I cleaned it all off on my 74 Dart Sport when I had the front clip off. When the fenders went back on, I did use a non hardening putty type sealer along both sides and re-installed the fenders.

The thought for me was to eliminate the metal to metal contact. If you have it all painted and sealed, then put it back together without it your gonna have metal to metal contact which in my though process would create bare metal spots in that seam from movement, thus encouraging rust to start.