I'm not sure that Central American flights are considered international flights when it comes to lounge access. I've just searched for the appropriate rule, and found this:

OneWorld Lounge Rules

Connecting between oneworld marketed and operated flights:

First and Business Class customers connecting on the same day of travel, or before 6am the following day, can access the lounge when travelling between an international long haul (a oneworld international long haul flight is defined as an international flight marketed and operated by any oneworld carrier with a scheduled flight time longer than 5 hours) and an international short haul or domestic flight (and vice-versa).

How long was your international flight?