[Vallen Chaos Valiant]

Originally Posted by orion

well i would have thought

Spoiler for ep.4:

that being a virgin would be nothing to apologize for. Seras was one. That's how she got entangled in this mess. At least Integral won't be a ghoul if she is ever bitten.

You misunderstood.
Seras was apologizing for drinking blood that was of the highest-grade that a vampire could ever aimed for. It's one of those "I'm not worthy" kind of apology.