One of the most prominent aspects of mankind's first sin is that in one sense, nothing spectacular happened at all. Lightning did not flash, and thunder did not crash and reverberate through the sky. There was no great earthquake; no huge crevasse opened at their feet and threaten to swallow them. We can take a lesson from this too: Most sins occur beyond the sight and hearing of others, and most people take pains to hide them.
Taking pains to hide one's sins suggests that if no one sees them, a person can get away with them, and nobody is the wiser. Even with this first sin, time seemed to move on as though nothing happened—despite being one of the most momentous events in mankind's history, affecting everybody born since!
Our first parents' sins are the first indication that no sin is done in a vacuum, that a sin can be committed that affects nobody else. In Scripture, sin is typified by leavening. No one must induce leaven to do what God created it to do. Like yeast, sin spreads and infects others.
This process also sets a pattern for God's reaction to sins that we commit. There is almost never any outward indication that one sins. Notice that God called out to them in the cool of the day, suggesting the passage of some time since the sin occurred. It was certainly after they had time to dress themselves in fig leaves. Perhaps God called out to them in late afternoon or early evening.
God certainly did not arrive on the scene in a terrifying manner—with fire, hailstorm, and thunder. Apparently, He was calmly walking. But notice that the Bible indicates that Adam and Eve reacted in terror of meeting with Him. The knowledge of their sin against their wonderful Creator filled them with great anxiety, to say the least. The sins were working internally, creating stresses in anticipation of His reaction. They knew enough about His character to know they had done wrong, and despite knowing they could not hide from Him, they nonetheless still attempted to do it.