I always assumed that over the events of AVP-R, Lex was just making her long ass journey back to civilization. Remember, all he had was that tiny moter bike, and the thing is bound to run out of gas. It's probubly assumed that by the time Lex gets back to the US, the events of AVP-R are done and over with, and she is simply interogated about the events of AVP, thus giving the Weyland-Yutani(?) corp. more insentive to begin even more space exploration.
