hiiii you didn’t miss it! there’s have been some hints but we’re at 90k word and it’s been weeks so i know i get lost and have to work hard to remember these little details too 😭😭 there’s a conversation that will be coming up soon between the two that i think will clear some of that up, so without spoiling too much future stuff ill share what we know so far :D hanbin introduced matt as a friend from new york in chapter 2, he explained hanbin tends to not talk about his time there in this quote “What he rarely talks about, however, is his family and the friends he made during his time there. Whenever Gunwook tries to push further, tries to understand exactly where his hyung came from, Hanbin steers them away from the topic. Never unkindly, but always firm.” so there’s already a bit of hesitance to talk about the people he knows there in the first place, gunwook is confused by it in general not just when it comes to matt but confused by who hanbin was before he met him. hanbin hasn’t really had too big of role yet mostly because of proximity in the fic, hao, matt and gw all work together so him becoming close to hao isn’t something suspicious, he even mentions talking about this with hanbin in chapter 4 in this quote “ Call him sensitive, whatever, but it’s not fair that Hao won his trust without even trying. Hanbin tells him it’s because of their subgenders, that they just have a different connection that alphas can’t understand.”

so from what he know right now, gunwook did initially question matt and hanbins friendship but is so accustomed to hanbin’s shiftiness regarding his past that he left it be (for now) and he does notice hao and matt are closer but attributes it to their subgenders being the same.
we’re about halfway through so there’s still quite a lot that hasn’t been discussed or revealed yet but it will be in time! i hope that cleared it up a bit and if not then no worries there will be lots revealed soon :D