It can be. That demonstration was used with the least amount of mana possible.

[ If he used more it could look similar to what happened when he used Selena's book with even fireballs, and at that point if the fire hit...well. ]

It is one of the most basic spells, so it was easy not to consume too much of it. Generally, I'm not going to wish to use too much mana either, even for something like this.