I have exactly the same problem as you. I put my iphone in my bosse dock station while it was partially wet; with the consequences that you know. I don’t think that I could use the warranty because even if we restore the iphone to the original status, I don’t have a contract with ATT or a valid sim card to show in the apple store. Even worst….probably the “humidity sensor” will tell Apple that we expose the iphone to unusual conditions.
So I’m sitting waiting to someone who could develop an application that stop the annoying message.
If you know something please let me know
Some other iphone users, fixs the problem cleaning the dock at the bottom of the phone, but it doesn't work for me.