I haven’t really thought about it 
The outer is the inner reflected, so perhaps this phenomena is simply that. My musings throughout the day generally tend to be inwardly focused a lot of the time. Even when I’m interacting with others I’m generally ‘checking’ some aspect of my self. Maybe observing is better used, there.
Of all of the ‘labels’ for spiritual identities, ‘sage’ is the one that has always resonated most. I’m no saint. Mystic always seems too…well, mystic. So, another theory would be that I’ve aligned with a sense of identity that ‘fits’ me.
I’m not the most sage-like individual; by that, I mean I still find faults in myself and others. Someone can say something I disagree with, or do something I disapprove of and I still have emotional reactions to it. So I don’t think that these signs are necessarily Universe saying, “Hey bro, here’s a sign you made it!”
No, for me, I - without really considering why - have considered these signs to be more of a nod in my direction. Sometimes it feels like I’m being given a thumbs up like, “You’re doing good. Keep it up.” Sometimes it feels like a reminder. Other times it just feels like either a “keep your head up” or when I’m feeling joyful…not sure how to describe that one, but another form of confirmation.
It’s funny because last week even my coworker mentioned it to me, saying "Foo, why is it that I see sage everywhere with your ass? “ lmao.