What should my friend do after immigration police requested to check his passport status at his condo?

A user shares an experience where immigration police left a message at a friend's condo wanting to check his passport validity. The friend's passport is valid for another four years, but concerns arise due to the unusual request. Other users respond with similar experiences, suggesting that these checks might be legitimate and hinting at a wider trend where immigration police are monitoring long-term stayers. Users advise verifying the identity of the officers and suggest leaving a copy of the passport at the lobby, while also recommending that the friend visit the immigration office to clarify the matter.