Sorry you're feeling bad about it.
Isn't it amazing the power you have over people? You can - just by your presence - cause them to run away scared!! Start thinking about shunning in those terms... about how JWs are just cowardly little bullies in a cowardly bully organization and their only defense is to run away and not speak to you!... and you'll start to see it in a whole different light.
The last few times it's been attempted on me, I was the one who shunned them! I have also laughed out loud and been very vocal about what was happening to onlookers. A couple of weeks ago, some JWs came in line behind me at the grocery check out after walking back and forth across the line of cashiers to make sure it was me. They started asking each other "Do you think that's Sister Scully?" "No so loud, you don't want her looking this way!" "Isn't she an Apostateā¢?" "I heard they put up a NO Jehovah's Witnesses sign on their door." At that point I was ready to burst out laughing. Fortunately one of my co-workers saw me and we started chatting as though the JWs behind me didn't exist. I shunned them! They had no power over me! But they were sure scared spitless of me!