Just took a flight on Monday from HOU to LGA (Houston to NYC), and I freaked out during taxi to the runway that on the left wing, 1 of the 2 "bulges" from underneath the wing was missing, revealing the exposed mechanical joint underneath. Both wings usually have two bulges that extend toward the rear of the aircraft from underneath the wing.

Admittedly, the visual disparity was probably more concerning than the underlying functionality. The flight attendants notified me that they had informed the captain.

After the flight, I asked him, and he said, "sometimes they crack" and are removed without being replaced.

This was a United 737-700.

Was I right to raise the alarm bells to the attendants? Were we ever in any danger? Should the ground crew have fixed this before take-off?