The “V” shape of the crack, wider at the top than the bottom, is telling you that it is foundation movement. Because you (they) did not see cracks on the inside of the house is probably because the brick is a veneer (non-structural). The true question IMO is this an old crack due to a one-time settlement after construction or a new crack indicating an on-going problem that could get worse? Look for clues. For instance, is the door threshold and step to the left flat and level? Old step versus new step (what Brian was pointing out)? Any telltale cracks in the sidewalk? And, so forth.
From my point of view that door is missing a threshold. Every home must have one egress door, and it must be a specific size, with a specifically dimensioned landing on both the interior and exterior side of the threshold.