I'm new here, but recently started using Alfred on daily basis. I've been having problems working with passwords so I've created my own workflow just for retrieving credentials through Alfred app for password store created with pass utility, the usage is pretty simple: just type p followed by a password phrase from your password store, then select matching entry and password will be copied to the clipboard.
I've written short blog post about it @ http://blog.konradwasowicz.com/magical-passwords-and-how-to-wrangle-them/ . You can find ready to use workflow on my github account https://github.com/exaroth/alfred-password-store. It's my first workflow so If you have any issues with it I'll be happy to fix them, also comments are super welcome.