It is. So is "She had a worrying look on her face" - the sentence asked about. There are many other good sentences. Even with the added context, both 'worrying' and 'worried' fit."She had a worried look on her face" is perfectly fine and natural.
A worried look on one's face would be worrying to others, wouldn't it?
A worried look on one's face would be pleasing to one's rivals, wouldn't it?A worried look on one's face would be worrying to others, wouldn't it?
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He has a worrying look. His lips pressed to gather. I was wondering if he would start crying.
Is this because nobody is likely to know whether other people would be worried by her look?You are not likely to ever hear somebody say She has a worrying look on her face.