Is the brownish spots on the front top on the iPhone 3GS normal?

It’s like 3 like spots that you van only see when held up to a light it’s by the top speaker

It’s like 3 like spots that you van only see when held up to a light it’s by the top speaker
Those are sensors to determine when the auto brightness adjusts itself and to also determine when the phone is near your ear during a call so it can turn off the screen while talking. This makes it so your ear doesn’t accidentally end your call mid conversation.
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