Well, wasn't that a fucking look coming off of Loki. Tony just stared right back, albeit with quite a lot less surprise and then, when his friend finally stepped back to let him into the apartment, Tony did exactly just that.
It was a pretty rare thing, for Tony to not immediately have something to say about, well, anything and everything, but he was momentarily quiet as he watched Loki clean up his clutter of work -- although Tony did make himself nosy and look over the paperwork before it was all put away and organized. It wasn't really what he was focusing on though, instead going over that look of surprise turned to contemplation, like Loki had been trying to deliberate just how to best deal with a surprise visit.
"I brought cake," Tony said, "What do I look like, some kind of pleb?" Admittedly, it was cake that Bucky had brought over because his neighbor down the way loved Tony for basically having become her IT guy. But it was still cake. Along with burgers, fries and a variety of other fried things, because Tony didn't have a budget anymore so he might as well just get whatever and let Loki be more choosy with the options.
He set down his bags of stuff though and offered Loki a cursory look that said he was suspicious before wandering off to the kitchen to grab plates and glasses. "I'm fine. Is everything okay with you?" Because he wasn't the one being weird here and he didn't appreciate it seeming like he was.