Uh, ANY contact your blood or open wound, no matter how small, has with anyone else's blood or wound is gonna put you at risk. It doesn't matter whether it's direct from your body to his, or on the straw. So yeah, get tested, though it's doubtful you'd have it. It's actually hard to catch, but you are still at risk.
Your friend really shouldn't be doing any drugs with Hep C. Naughty.