If a frozen feeder I knew hadn't been thawed or partially thawed turned up with blood on its nose, I would definitely be wary, though I doubt I would throw it without at least thawing it. Just wait until you thaw a mouse in a fully-sealed bag and it comes out decapitated. I'm not squeamish, but that was really gross.

Our pastel's burst yesterday and she didn't care at all, just chowed down on it. She had to kind of hold it together with her body, though, because otherwise it would have all squished out before she could get it down.

(Also I know who you named your snake after ;D)