Hulkling's Hardened Spikes bug

I just played a match in which the enemy Hulkling used his purple power to put a yellow countdown on the board. Hardened Spikes has the following description:
"When this tile is on the board, Hulkling takes 10% less damage from matches and abilities, and deals 259 damage to enemies that damage him with matches or abilities. When the Countdown tile expires or is destroyed, heals a burst of 370 health and this ability becomes Metamorphic Adaptation."
I removed the countdown tile with Colossus' Neutralization, however Hulkling didn't switch back to Metamorphic Adaptation. Is this because I removed the countdown rather than destroying it? Or is the presence of the countdown only checked on the following turn? (I didn't leave him alive for another turn so couldn't check that, but he did take Colossus with him due to the Hardened Spikes still being active.)