Happened exactly as you said, waited until my next extension of stay and told them about my forgetfulness. They cut me off finishing my well thought out reason and pointed to the 90 day report desk. Went over, said itslate, he pointed to the 2000 fine message and i showed him the money. Did my 90 day report, he asked me about my extension of stay then he printed me 2 copies so i didn't have. Nice guy, no fuss. 😏