Does your device have the correct time (and zone) set?

I double checked and it does. And the timestamps of all the other submissions seem to be correct. Only that particular one is wrong.

Plus I don't think the local time setting should affect the HN's ranking algorithm.

This may not apply to HN, but I wonder about sites that use JS in the page doing clever timgs with time and apparently ignore the possibility of (at least) skew between local time and time at the server.

I remember doing sysadmin for a client with machines out in the field many timezones away showing apparently the right time, but with a bodged zone! Took me a while to understand what was going on! I think we probably fixed the issue properly after discussion!