You say that. The FA's open/close , arm/disarm the doors day in day out. I arm/disarm the doors once every three years on a line check.
Someone may know how to microwave their breakfast every day but not have a frikin clue what to do when it pops a c/b. Flight crew has the responsibility of making the call, so yes send Jr. back to have a look. If the F/O is unsure BACK TO THE GATE!