Could be that.  
I thought might be a stealth nerf or something of the sort with the recent -10% MS.

Her passive is occasionaly procced without it being shown and also will be reset without showing it if the criteria are met, however with all of the hitreg and latency issues the game has right its more likely an unintended issue rather than a change

I used to play bangalore a lot (got almost 2k kills so i have a bit of experience with her)  
Lately I feel like she barely procs her passive, not talking about the movement speed it gives, just the amount i proc it.  
Did anyone else notice that? Didn't read anything about it in patch notes when they gutted her

Bang's passive