Gilbert doesn't seem to notice or give any hint if he is responsible.

He looks thoughtful, though, considering options. It's possible that the portal residue is what he has identified on Five and his sister rather than their powers. If it's enough like the Abyss... then it may be possible to recognize them without confusing them for the surrounding world and its powers.

"In that case, my colleague is better at hunting residuals, but I think it's possible I could sense them as long as they exist in the present. So if they arrived here in the future, it won't register until our timelines synchronize."

It's a hard guess, though. Meanwhile the feeling doesn't let up, but it doesn't enroach any further, either.