Probably an A319. The bags etc are loaded in the aft cargo holds for performance reasons (nose down trim).
If someone has faffed around and thus had a delay in moving people forward AND the baggage handlers are late/delayed then it is possible to get a nose light situation.
First thing that the crew would notice is the distance to step down to the exit. Next thing would be an alert from the flight deck saying the nose gear is at full extension.
The A320 is longer and to prevent the above, luggage is loaded in the fwd holds.