I don't know about you, but I jumped on the Hannibal bandwagon a bit late. It wasn't until Season 2 that I started watching the series as it aired, and it was even later that I started following its social media accounts — which is why I only just discovered this little tidbit (which came to my attention while I was perusing a Fannibal Facebook group, after one of the members reposted it from the Hannibaland page):
Fuller posted that tweet nearly a week after the series premiere, during which we see Will Graham do his this-is-my-design trick for the first time. (It might seem crazy to think that Fuller was planting things like this as early as the pilot, but those familiar with his work know he does nothing by accident. It also has me pretty excited to see what other kind of callbacks we might get in the future.)
If you go back and watch the scene in question, it's not all that surprising that these were Dolarhyde's first kills — you can see that his methodology wasn't nearly as airtight as (I assume) it will be by the time he's introduced in Season 3.
For instance, in the novel Dolarhyde waits until his victims are asleep, then quietly sneaks in. Here, he literally kicks down the front door, gun blazing, and, apart from the precision with which he shoots the couple, doesn't calm down and start exercising the level of caution he displays in the novel until after Thomas is dead and Theresa is on the floor (at which point he uses his pre-taped recording of her answering the home security system questions). At least we know he was employing similar surveillance tactics even when he first got started.
I'm interested to see what kind of callback we'll get to the Marlowe murders — perhaps an "Aha!" moment for Will, during which he realizes he's seen Dolarhyde's work before. Or, it might be something as simple as running DNA from one of the newer murders and finding it's a match with the Marlowes' killer. Either way would work well toward Will and Jack working out how Dolarhyde has evolved — and maybe put Will in the position to blame himself for being unable to find Dolarhyde earlier on in his career.