Aragorn heard his beloved curse when they entered the Mines. He had never once heard Shadow use foul language and became worried that the Elf had been injured. But before he could ask Legolas if he was alright, Gandalf was on the move with the Elf following close behind. The Man decided that he had erred in not binding Legolas to himself the night they professed their love. He would speak with the Elf and complete the ritual as soon as they had some privacy. Aragorn could only hope nothing bad would happen before then.