Yes, stress-related. Magnesium and the B Complex Vitamins are ESSENTIAL to HANDLING STRESS calmly and smoothly. And stress DEPLETES these nutrients.
Magesium deficiency can often cause twitches, tics, tremors, etc.
Some of the safer and more effective forms of magnesium include: Taurate, Glycinate, and Citrate (the latter can be laxitative -- take with food).
In my opinion, it sounds stress-related.
If these twitches become more often, lasting longer and start to involove more parts of your body, I would recommend consulting a Neurologist.