Depression usually implies a greater span of time.
In my experience, I had bouts of depression lasting anywhere from a few days to a year, but between periods of depression were moods that I could describe only as neutral; no happiness but no sadness either. Obv this is a pattern of bipolar disorder and not the way typical "depression" that most people go through works, but the depression itself is the same, and it sucks.
In the case of OP, I would hesitate to call it depression unless there's a clear pattern of negative feelings and thoughts for a prolonged time.