Lex could see that Tetsuya was nervous, but was hiding it well. It was good to see that after a few years, he had tempered his personality a little. Based on how arrogant he was back on X-142, he might have already inadvertently offended Lex. Or, well, considering that he had already made an enemy of the Empire that ruled this planet, maybe he hadn't improved as much as Lex imagined.
He would see for himself, since the next set of guests coming to the Treehouse seemed to be from the Empire. Or, atleast, that's what Lex assumed considering that a military convoy was heading his way.
It wasn't enough to be called a small army. It was more like the protective detail for a high-value member of the Empire.
Lex also considered that they might be after Tetsuya, seeing as how they were coming from the same city as him.
