They should indeed have been swapped - in your place I would have asked for a plastic one (but accept it's not always easy).

Do note though that Mainline and CityFlyer are two totally separate airlines (albeit with a common branding), and as such have totally separate safety rules and practices. Much is the same (both because it's common sense and because it's CAA/EASA-led), but there may well be differences in SOPs on certain things and it is therefore wise not to assume that they always follow the same procedures.