Not every character’s voice is grammatically correct. As a fiction writer, this puts you in a position where you have to make a choice: stay true to the guidelines of grammar or stay true to your character’s voice. And, as you note, those additions of “and” make a difference. Sometimes, as a fiction writer, you achieve authenticity and develop character at the expense of grammar.
That being said, such choices shouldn’t be made lightly. First, make sure you must make the choice. You might consider the sentence construction that leads to your question. You mention it happens often with this narrator. Is that an authentic aspect of the narrator’s voice? Does the repetition of that construction add to the individuality or distinctiveness of the voice? If you’re not sure, you might experiment with other possibilities so that the repetition isn’t as prevalent. Voice should be constructed carefully.
Consider, too, the dynamic that sentence construction creates. Is there a connection between the events—in this case, the leaving and the calling? Does your choice support that? Notice the subtle but different emphasis with this change: “Figures he’d call when we took off.”
All this is to say, don’t be unnecessarily bound by grammar and don’t use this freedom as an excuse to avoid going deeper into characterization, voice, and the possibilities of language.