How can you tell if a bottle nipple isnt good anymore?

I just washed my daughters bottles and left them to soak in the sink a bit longer than usual I guess and i washed, rinsed and sterilized them and now some of the nipples arent really clear anymore their almost white? This has never happened any other time so Im just wondering does this mean they are ruined and need to be replaced? majority of them are fairly new since I just switched to the fast flow ones