"Get" is doing some interesting work here: it's an active verb doing something rather similar to the copula, "to be," in that it implies the initiation of a state of being. This lets you produce a kind of makeshift subjunctive or future tense to refer to a state of being that hasn't started yet ("don't get upset!") without using the more cumbersome "become" ("don't become upset!").

In your example, "If he contacts you" is indeed better, because it is an active and not a pseudo-passive construction and thus more direct. (It's also less informal.) But this is no surprise: people rarely think in a straight line from A to B!