Heimerdinger's turrets

I was playing Hexakill just now and Bard had just killed me after taking the right altar when I realized that the turrets were shooting at Bard even when he was well out of range and vision. The stopped on deactivation, but upon reactivation, they were still shooting at Bard, with no damage being done, while he was invisible to our team via a bush. I don't quite know what caused it, but this makes me feel cheaty with the infinite-vision it provides. After destruction, the turret stopped, but I don't know if it did that again as my turrets were promptly destroyed immediately after me afterwards.