Animist's Awakening triggered Gem reappearing

Gargoyle

I don't know how to repeat this but the last time I cast Animist's Awakening something weird happened; the 1-turn Special gem triggered at the start of my turn as expected, but after the gem was destroyed the fall of the above gem paused and a Loyalty Gem appeared in place of the destroyed Green gem instead. The above gem was coloured(Red), so this wasn't just a visual bug; the game literally generated a random gem instead of dropping the above.