You simply saw one of the hundreds of mine/farm bots infesting this game that SE aren't doing anything about and didn't put in any server-based mechanisms to detect and prevent. SE show no signs of doing anything about it, it's got worse and worse, some crafting mats like Fleece are impossible to get legit as all the mobs that drop them are being multi-botted, and not just by RMT I've seen known raiders in high profile FCs running bots.