When encountering an interruption, the mind takes a step back and begins to think on a broader scale. The effect of has been well documented, but what's so interesting, according to Keith Sawyer's blog, is that the benefits of so called "global thinking" tend to linger after the original problem being addressed. The abstract he cites references six total studies on how the presence of obstacles triggers a broader take on the situation at hand, one of which concludes rather academically: "Conceptual scope increased after participants solved anagrams while hearing random numbers framed as an "obstacle to overcome' rather than a 'distraction to ignore.'"
Non-academically, context matters. Positive emotion contributes to expansive thought, and, in fact, a growing body of evidence from happiness studies links the two. In addition to the new information about the expansive mind - the effect can linger - the study reinforces the point that we see the world as we are, not as it is, and that, depending on whether the obstacles are viewed a positively or negatively, we might solve, or run, from the challenge.
Perhaps that's also part of the dizzying effect of falling in love - new possibilities and alternate futures become available, materializing in that comely woman or that tall and broad shouldered man - or why, in the course of normal development, children are so uninhibited and think so creatively. Everything in a child's environment is a challenge to her. With the energy of youth, she confronts them.
Just some thoughts.