@chrischewie
The morse code was done shortly before Lalo or Usogui (presumably) know about the participation of Fukurou and Hal. In Lalo's defense, Usogui's behaviour was simply a desperate front after taking the calamity or a mnemonic device.
Also, I think Lalo is a more straightforward person. Usogui always think up about ridiculous possibility in all his gambles so far but Lalo always resort to brute tactics, i.e. like how he raised the bet so high in the 1st round before knowing the air poker law. So it's within Lalo's character to not notice Usogui's morse code. Lalo is perfectly capable of being reactive, but he lacks the craziness Usogui have.
Anyway, I really like how Usogui and Hal's fated meeting is the key in winning the gamble. And nobody knows about Usogui and Hal deeper connection, not even referees. On the surface, Usogui's and Hal's relationship only go as far as challenger and challenged, but we as a reader knows that their relationship is much more personal than that.
Can't believe that a gambling manga managed to give me the feels like this.