by itself usually doesn't cause hypo(except in very very rare cases), unless you are on other diabetes
medications too along with metformin.
At 2.9 (52 mg/dl), you should have experienced hypoglycemic symptoms, which you didn't. I have a strong doubt that there must be an error in the instrument (glucometer).
I wouldn't really worry, but since you stay alone, it's a good idea to make a visit to your doctor.