Rubin et al. (Reports, 16 June 2017, p. 1154) proposed that gradients in lithium abundance in zircons from a rhyolitic eruption in New Zealand reflected short-lived residence at magmatic temperatures interleaved with long-term "cold" (< 650 degrees C) storage. Important issues arise with the interpretation of these lithium gradients and consequent crystal thermal histories that raise concerns about the validity of this conclusion.