Often in Tanach, a large amount of time passes over the course of just a few Pesukim. One can easily miss the passage of time, since the reader tends to perceive events that are described either one after the other or shortly thereafter in Tanach as having actually happened in immediate succession. As an example, nearly forty years pass between the story of the Meraglim in Shelach and Miryam dying at the beginning of Chukat, two Parashiyot later (and there’s a Machloket Ibn Ezra and Ramban if the Korach story happened in between, as portrayed in the Chumash, or was actually before the Meraglim story), but when learning that section, one could easily think of the events as happening at relatively the same time.
In Parashat Shemot, there is a similar phenomenon. Moshe runs away from Egypt shortly after becoming an adult and does not return until he is 80 years old (Shemot 7:7). Ramban (2:23) assumes that he was no more than 20 upon his escape from Egypt. Now, it is unclear how much of that time was spent in Midyan, the only location mentioned in Chumash as to where Moshe went after Egypt. Ramban posits that Moshe first arrived in Midyan towards the end of the approximately 60 years, since he is described as having only one child before being chosen at the Seneh (Shemot 2:22), yet he has a second son in the beginning of Parashat Yitro (this second son is very likely the same son who receives a Berit during the obscure hotel story towards the end of Shemot Perek 4). If Ramban is correct, that leaves many years unaccounted for. There is a story recorded in the Divrei Hayamim DeMoshe, describing how Moshe became the king of Kush during that time. However, this story is not found in any authoritative Midrash and the Ibn Ezra (Peirush HaAruch 2:22) is very disparaging about its authenticity. Interestingly, Rashbam (BeMidbar 12:2) accepts the story as true and uses it to explain who the Kushi women was that Moshe is described as having married. Rambam theorizes that Moshe was a fugitive for the bulk of his years away from Egypt, never staying in one place for very long. Only towards the end of the 60 year period did he settle in Midyan. Ramban employs a methodology that he often uses in Tanach to explain why the Chumash does not report on those years. He believes that when nothing of great significance happens over a period of time, the Tanach simply skips that period in its narrative.
Regardless of which approach one takes to account for the "missing" years, I believe that a significant lesson emerges from the time gap. The lesson is particularly relevant to our society of instant gratification, and that is that things often unfold slowly. Moshe spent decades wondering if he would ever return to Egypt, yet ultimately, it was all part of Hashem's master plan for the Jews' redemption. We should often take a longer view in evaluating how events develop in our own lives as well.