Nokia 6230 water damage?

I have Nokia 6230 ,for about 10 months now. about 4 months into owning the phone it was submerged in coffee for about 2 hours i dried it out and the phone works just as good as the day i got it u can see some stain on the screen. about a week or two ago my phone just stoped getting a signal and i called cingular and they said they have had many people with the same problem with the nokia 6230. They said they would replace it under warrenty. My phone was water damaged but it works fine the leads are fine the tags are fine i guess my question is are there any water damage indicators on the 6230 (because i dont see any or cant find them) or is there any other way they would find out it was submerged the guy i talked to on cingular exchange told me they useally check the leads and to see if the phone turns on and thats it any advise at all would be great