Had the moon been captured, why are we losing it? Well, after zillions of meteoric impacts, I guess the moon IS losing weight. (And so is Earth).
There's a tidal transfer of momentum between the Earth and Moon which over time has slowed down the rotation rate of the Earth. Due to the smaller mass of the Moon (1% of the Earth's), the rotation of the Moon was simlarly transferred to the Earth, the Moon just finished first and now shows the same face. Over enough time, the Earth will either push the Moon away (that'll be a bad crazy day) or will wind up showing the same face to the Moon, as the Moon does to the Earth right now.