A normal peak aortic valve gradient is usually less than 25mm. This is typically obtained via echocardiogram using the Bernoulli equation [Gradient = 4(velocity)² mmHg]. 27 may be mildly elevated but certainly not too concerning.
I'm not sure what the thumping sound you heard was, but if your click is audible and suddenly stops being audible, there could be clot or fibrous tissue on your valve which can plug it up. This is usually accompanied by symptoms of severe shortness of breath and chest pain. It sounds as if your valve is working relatively appropriately.
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