I still think its just Nick. I remember immediately being suspicious of him because he was searching for the laptop in the library after it had already been found and recovered from the library. And I remember at some point he tells another DIK he had met Vinny recently. Like the previous week or so. It didn't make sense to me why he was so gloomy and nostalgic and missing Vinny if he was keeping in touch and so recently.
Now, with all of that in mind plus the raid on the house having not touched Nick's room, Nick's behaviour to me seems less missing Vinny. And more, missing the OLD Vinny, since current Vinny is a drugged up psycho pushing Nick to betray the DIKs over revenge. Nick's behaviour is of someone caught in the middle, trying to decide between his loyalty to Vinny or to the DIKs. Thats my take, at least.