Not at all unusual, the BA run lounges in the USA would get over-run with AA and AS refugees and so there's a near blanket rule that access is for the designated services. PHL lounge often features here, since it has a prominent location in the airport. BOS, since the joining up of the other concourses and terminals now gets raised here, even though it's a huge hike from the AA terminal. I guess we hear of an incident like this in this forum every 3 months or so.