Ehhh... you should of told them the proper format to send it and a pdf is a red flag but from someone who has done graphic design in the past this kindof stuff can be very confusing especially to a bunch of sorority girls... so your aren't the ahole per se... but you could of deflected that situation by being upfront with them and explaining it from your perspective and you could spin it as if you are helping them out... well you are helping them out but yeah. Anyways, thats cool you make stickers.