I thought maybe it was just because I was eating tough jerky, but then it happened again today at dinner while eating a salad. My temples got tight and so did my jaw. Again, I opened and closed my mouth and massaged just below my temples. It took a little longer for the tightness to fade. 

Should I be worried? Is this a significant, or normal end of pregnancy symptom/experience?

My history: I have gestational diabetes. Around 32 weeks my feet and ankles started swelling. My meals are managed and my levels are looking good. The swelling is still building, though I try to keep off my feet. I am pretty large now and my baby is weighing in about a pound and a half heavier than he should so I imagine that is related to the swelling. I spend a lot of time driving for work and when I am at work it's not too demanding. I feel I'm doing what I can for the swelling and my levels. 

Just not sure how to respond to the jaw tightening, it's pretty scary when it does happen. Anyone who can relate?