For almost 4 years after his training in the ways of the Force with Master Obi-Wan Kenobi, Luke Skywalker had kept with him the lightsaber that once belonged to his father; then, Luke first meets Yoda in the swamps of Dagobah. While Luke was setting up a temporary camp, the sudden, unexpected appearance of a small creature caused him to draw his blaster.

I ask: why was Luke, after having directly experienced/felt the power of the Force, more likely to reach for his blaster than his lightsaber to deal with an apparent threat?