To be fair to them, they do not say, "It doesn't fit." It's more of a steady series of gate announcements saying that the overhead bins will be full and Please come to the gate to gate check your rollers. They don't phrase it like "IF the bins are full, then you MAY need to gate check it.." And when I look around the gate area, very few people have a roller. PSP is definitely a more laid back airport.