Not everyone's mucas plug is tinged pink. So it's possible that you are loosing yours.... When I was pregnant with my daughter, and I started to loose mine, it was a yellowish color then it turned to a snotty green color.....It's not alway's pink or red like everyone say's...... And even if you are loosing it, don't worry..... Your past 33 week's which mean's the baby is fully developed lungs included.. (Lungs fully mature at 33 weeks) so if the baby is born now, he or she would just be small... :-)
It COULD be or it could be just a normal increase in regular discharge. Typically a mucus plug will be atleast tinged or streaked with red or pink. But it doens't necessarily happen that way with everyone. There's realy no way to know for sure other than to ask your OB to check. BUT keep in mind that some women lose their plug 6 weeks or so before going into labor. It could just be your body preparing.
It sounds like you may be loosing your mucos plug, but it is hard to be sure because at the stage of pregnancy you are in there is normally an increse in discharge... I am 37 weeks and I began loosing my mucos plug at 35 weeks and the only reason I know for sure is because mine was pink tinted.. (tmi im sorry) I would mention it to your Obgyn at your next appointment... Best Wishes.