This will sound like heresy but we actually can worry too much about sanitation. Beer spoilage bacteria (not all bacteria can survive fermentation) usually is outnumbered by yeast. Generally the really nasty bugs build up over time, like an unclean port or dirty lines. For me, when a sanitation error happens I usually don't sweat it too much but often times, depending on the severity of the accident, I will plan not to harvest the yeast from that batch and start fresh. even so, in most cases (like dropping the vial) you will be fine since there probably isn't much that can live on clean plastic. And, FTR, with vials and smack packs I always sanitize the whole package before pitching to account for accidents such as this.