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If I remember correctly, that is normal. The charge can fluctuate between 97 and 100 percent, to keep the battery from taking damage from being plugged in all the time.

(I could be wrong, though.)
 
i think this happens because the battery stops charging when its full as a way to protect the battery. the computer is running on power but still occasionally uses the battery resulting in the battery being stuck just below 100%.
 
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