Yesterday on DL 1393 I witnessed a first, at least for me. Preboarding began with 3 passengers in wheelchairs. GA announced again, "anyone who needs extra time to board please come to the gate." An older couple gets up (no apparent assistance needed), with their small dog on a leash (no apparent service dog ID) and are allowed to board. Young mother with an infant follows, and is rejected. I wasn't the only one in the immediate gate area that shook my head in disgust/bewilderment.