I would just take a pregnancy test to be safe. Although late periods can be cause by a number of things, including stress.
If you're still concerned I would talk to your gyno.
Several things make us late for our periods which include stress, illness, changes in routine, traveling (as you did), weight gain or weight loss and really, it can happen just out of nowhere. Since you ARE late, you can take a home urine test to double check. If negative, wait one week and test again if your period doesn't show. My guess is that it is late and will arrive sometime in the near future.