Tia looked incredibly guilty when Erich interrogated her about what she was hiding from him, and in the end, she could not openly lie to her master's face. Conceal certain truths from him? Sure, so long as he didn't ask her directly about it. But when Erich asked her so blatantly, she could never outright lie. And thus she started bawling as she told him what she had come to suspect.
"Master, it's not that Tia is hiding anything from you. It's just that Tia has yet to confirm whether or not her suspicions are true, and thus did not want to worry you. But if you really want to know why Tia is so anxious, it's because she suspects that we may be facing an invasion from a Second Naraku infested Galaxy, and potentially as a coordinated assault with Andromeda.
