Rust our of vent line??? HELP!

Is there any concern here? I have what appears to be rust coming out of the HVAC vent line? Anyone know what causes this and why? Thank You!

A rusted drip pan. The rusty color on the stucco is not from this condensation line.

just got out of the attic and you nailed it! should have waited tell then but you never know these days…thanks Jeff!