Coughing Advice for coughing piggy?

So one of my girls started coughing today. I was sitting on the cough after giving them their morning veggies and I heard one make a weird noise with the water bottle (sounded like she hit it or pushed it out too far or something) and then a very loud cough. This is the first time I've heard either of my piggies do this but I assumed she ate too fast. About an hour later however I had her in my lap and she coughed again! Is that normal if she ate too fast to be still doing it an hour later? Should I take her to the vet or watch her for now? At what point should I take her to the vet? Thankfully I live near a college with an amazing vet program so I'm not too worried, I just don't want to waste money if this is nothing.