I've noticed a few people complaining about how they couldn't find another Gooda Vine in Trynton. I thought it was weird, since the first time through, I found them without any difficulty.
With my fifth party, (and third to get to Trynton) I rapidly clicked on the area of the vines three times, and ended up with one vine in hand. I dropped it in my inventory, and then clicked around some more. Ocassionally the cursor would change to the hand, but I could never pick up another vine, and there were no dropped objects on the radar. It seems that rapid clicking can cause the first vine to disappear -- maybe it gets burned up?
Anyway, I'd just saved, so it was no problem to reload and do it right, but had I not been through already, I might not have realized what had happened, and by the time I had figured it out....