Building glass tiles from glass seems to ignore the material's temperature. They are always built at around 45 degrees Celsius regardless of whether the material was at 1000 degrees or at room temperature. When deconstructing, the dropped material keeps the tile's temperature resulting in relatively easy method for heat deletion.
On related note: Molten glass freezing point lies 300 K below glass' melting point meaning within this temperature range the material can exist in either state.
Steps to Reproduce
Build a glass tile from glass right after molten glass freezes and observe its temperature.
This issue has not been confirmed by a developer yet.