Oh, You’re Back
Hey, guys! Did you know that if you go on vacation, that doesn’t mean you’re going to leave forever? We don’t have to tell you that, but someone needs to remind the higher-ups at the OP’s former workplace what “going on vacation” actually means.
Apparently, their former bosses thought that the OP was going to be away forever, even though nobody travels to Hawaii indefinitely. Not only had the company not bothered to ask when the OP would be back, but they hired a replacement during the brief time the OP was away. It sounds like they were looking for any excuse to replace you, OP.