[Sephiroth is a bit amused.]

Yes, I doubt you could have a roommate and not know it.

There's still the possibility it might not be a normal sickness.

[Which is true. He's not sure what he thinks at this point. It seems normal enough. He's confused by how fast it came on, but it's possible it was festering for a while and is only coming out now after Zack was so active in the fight.]