It appears water is getting behind that trim piece and rusty water is coming out the bottom.
I'd be concerned.
Not sure how I'd address it though. Maybe refresh the caulk along the top line shown in the pic? Above the rust.
Jim and Carol, plus furrballs Riley, Nikko, and Kobi
2017 Entegra Aspire, 2008 Monaco Knight, 2000 Fleetwood Pace Arrow