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I flew on JetBlue Flight 1011 BOS-ORD today, 2017-01-14. At the arrival gate, after 2/3 of the passengers had deplaned, a flight attendant asked us to stop and wait. He told us that the pilots were concerned that the plane was "tipping" to aft. I overheard the pilot say that the front landing gear was fully extended. The pilot also mentioned that they had "never seen anything like this," that there was no cargo on board, and that the baggage handlers had 30-40 bags remaining at the rear of the plane. After about ten minutes, we were all allowed off.
Why would something like this happen?