That brings up a good point... the datetime strings are saved in the server according to the server time, but afaik, we don't handle timezone translations, so if you're in a different timezone than your server, you might see incorrect relative times 
Seems like something we really should have, to translate ISO date strings to the proper timezone offset based on user preferences... gh#1994
I need to review how we handle the relative time generation, because it seems to be working fine at the moment (our server is UTC, I am EDT, relative times appear correct for me). Are the relative times incorrect for you?