I agree with the others that if they were close enough for you to hear them running, then without a doubt they were close enough that one of thier keen senses, wether it was smell, sight, hearing, or the 6th sense, they knew you were there and it meant danger!
You will need to change your set so as to get all the advantages in your favor, you can't do a set and hope that they won't see, smell, or hear something that's not right. I have seen coyotes that I was sure smelled me from 150+ yards., and if they detect any little movement that is not natural, they don't stretch there necks out and take another look, like a turkey will, and if they smell you, they usually will run as fast as if they had been shot at.