Not quite the same, but when passing folks on the MUP or link-paths (like MUPs linking roads/city ride routes) I always bell and sometimes "on your left" if needed. Well, last night I was on a link-path and rang the bell, I slowly passed a lady and as always, said a "thank you" when I passed her (as she moved WELL over and moved her bags in front of her, out of my way) - she actually replied with a "You're welcome, thanks for the bell!" - quite shocking - I kinda laughed out loud I was so surprised. I often do get a "You're welcome", admittedly, I've found the past couple of weeks now that there are many more people on the MUPs.

It's nice to have that positive re-enforcement.