Could my night blindness be due to a malabsorption of vitamin a?

Possible: You need to ask your eye doctor about this. Vitamin a deficiency is one of the reasons for night blindness but there are other reasons.

Night blindness: True night blindness or nyctalopia (from greek νύκτ-, nykt- "night"; and αλαός, alaos "blindness") is a condition making it difficult or impossible to see in relatively low light. It is a symptom of several eye diseases. Night blindness may exist from birth, or be caused by malnutrition (for example, a lack of vitamin a). Blood levels can be determined with normal range from 50 to 200 mcg/dcl.