That's new, we thought! What a cheesy mess!! The milk is fine in tea, but must be just "on the turn", and as it heated up, some began to curdle, then splat! It was such a noise we thought the cup had exploded too.
Be warned!!
We live in the "frozen north" and have never had to put the butter in the fridge. It is still a gamble how long to nuke it for to avoid breaking the knife.