Man, good on you for getting those shots when nobody else could even see back there, grainy or not.

The part about your coworker making it feel like a "grandpa word" is what gets me, because I used to swear this phrase was dead for good. I really did think "cool beans" was done, like it belonged in the same trash bin as "rad" and "gnarly." Then I kept hearing it pop up, but not in a normal way, more like a little wink, someone saying it to be silly on purpose. That's when it clicked for me that it never really came back for real, it just became a joke you say when you want to sound old on purpose. So yeah, it died as a plain everyday phrase, but it lives on as a goofy bit. Your coworker is probably doing the bit without even knowing it.