Missing letter/event?

(I play on PS5) I was checking my mail, and there was an unsigned note that I swear said "Meet me at the diving pier at 6 p.m." I've gone there twice now and nothing triggers. I tend to go through the mail fast so I tried to find the letters in the journal under Letters to re-read it, but it's not there. Does anyone happen to know what that letter was/said? I can't find anything on Discord or just searching online. Thanks!