Chest pain could be caused by any number of things, the most likely possibility of which is indeed a mucus plug. It's hard to tell just by the description of "chest pain." Was it localized to one area? Was it on one side or the other? Was it a throbbing, sharp or radiating pain? Did is linger even after you stopped vesting? If it continues and is accompanied by shortness of breath (more so than usual) be sure to let your doctor know.
Not sure about the g-tube. I hope things work out well and that you'll be feeling tip-top as you celebrate Thanksgiving!