I'm sitting in the lounge at LIS where my fiancée and I used the self-service check-in to get our boarding passes (having checked in online yesterday).

I've just noticed that her boarding pass says "Gate closes 1815" whereas mine says "Gate closes 1835" for BA503 to LHR at 18:45. We all know that gates generally close 10 minutes before departure, but it is strange that my fiancée is told it is 30 minutes before. Is it because I am Silver and she is Blue?