New paint cracking on caulk bead along exterior trim and j-channel flashing
Maintenance-free siding materials are typically installed with a loose-fastener arrangement because they're floating and move a lot with temperature. It's not common to see caulk against the various components for this reason. What you're seeing is somewhat expected due to stretch in the caulk. 

Your siding is a protective and aesthetic covering over a "drain plane", usually a layer of house wrap or similar. This provides the ultimate protection against water infiltration. The drain plane normally includes adhesive or metal flashing to door and window flanges. 

By the way, the siding and channel are probably steel. Aluminum isn't often used for siding anymore, as it's fairly soft and more expensive.