Is it bad that I can hear the heartbeat of one of my baby mallard ducklings?

The little guy is still in his shell and there is a little hole in the shell coming through. The duckling is hatching a day late, it is the afternoon of the 29th day the eggs have been incubated, but he is chirping and wiggling around trying to come out. I opened up the incubator to check on him when i noticed a strange clicking noise coming from the egg. The clicking noise is consistent and I'm pretty sure that it's the heartbeat of the duck. Is it bad that I can hear it, and if so what should I do? Please help I'm really worried!