I am a big believer in anonymity - as one of my past post has shown - and I think you definitely should at the least, telll your sponsor your disaproval of your 4th step being shared with others.
Before doing so, I recomend you consider a few things regarding your question:
- Why does this bother you?
- Did your sponsor share your private info with the other person... Or was it just the fact that you completed your 4th step?
- who did your sponsor tell it to?
--> was it a newcomer who may benefit from knowing another person is going tru the steps like them?
--> was it someone like a group leader or a person whose been a big part of your sponsos sobriety?
I feel your concern, and I would be asking the same question you are also...Speak with your sponsor but remember this: You reached out to your sponsor for help. You saw something in them you liked. A sponsor is there to help you not hurt you.