There's another thread somewhere where somebody's said that the screencaps of Daniel Faraday's notebook from last season and the one from this episode are not the same, so they were wondering if there are two copies of the notebook.
Maybe that's what Ben's taking out of the vent -- the notebook. It would likely contain things like coordinates and such, right? And wasn't Ben on his way to see Mrs. Hawking right after that? She might need the notebook.
I think this is another example of something I've been saying in countless other threads. Little things keep changing all over the place and I don't think that they are production errors. I think it's definitely on purpose and they are trying to tell us something with it.