1+ (the lowest level of finding) polyphasic potentials in one muscle is nothing to hit the panic button over. The EMG does not support either acute or chronic denervation, as must both be present in multiple regions, along with various clinical findings, to diagnose ALS. This result suggests at worst an old injury or benign oddity to do with that muscle.
Follow up with your neurologist, but the excellent news is that you don't belong here.