Hi,
From your question it is unclear how do you measure server response time. Is it some metric that you are using or some custom test you are performing to get that data? If it is some custom test what kind of test it is? Also, you could measure response time from client side until server response or just the server response time. In the first one will be very much depended on the network from client to the server.
So, it could be normal, but it can also be abnormal. It needs additional investigation and exactly how you do this monitoring.
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