Late Period Due to Stress?

Hubby came back from boot camp on Friday. I was supposed to get my period yesterday, and normally I spot the day before. However, I have had no spotting and no signs of a period. My period has always been regular with 31 day cycles. Could it be two days late due to the stress of getting him home from boot camp? Also, before Friday I had not had sex for over 3 months so there is no possible way that I am pregnant. Looking for opinions or advice!