Sunfire damages turrets?

Not sure if sunfire is supposed to damage turrets, but while playing with my Fiance, her sunfire did damage to a tower. I'll do my best to reciprocate it tomorrow, and test it again.

She was playing in a bots game, as rammus, against top lane out tower, her ultimate was down, she was not using the thorn-ball ability thing, nor did she have dragon tower-burn Things get really strange.