Lugia smiled as she heard Zaros' words, for it was not the first time she had heard them and in fact, she fully agreed with them, but she still felt some dissatisfaction.
The dissatisfaction was not because she did not like Zaros' words, but because she knew they were true. This meant that Andrew could become a hero in times of need, but she did not want it to come to that.
In her mind, Lugia wanted Andrew and his guardians to be strong enough now, so that they could take part in the battle they were about to face.
She knew that if things came to the worst, many bad things would happen before Andrew could rise as a hero. Heroes do not appear out of nowhere, they are created, and that only comes from misfortune.
She did not want Andrew to have to go through that. Not because she felt bad about the fact that he might have to suffer, but because of the fact that many would have to before he could take a step forward.