I'm having the same problem with two different computers. It seems like something changed in one of the two places, dropbox or Alfred.
I checked my Spotlight Privacy. It's empty.
I used Spotlight to search for the same file "ws-logo" - Returned multiple results
I used Alfred to find the same files - Returned with Internet search options.
I'm now reindexing.
More to come.
///UPDATE//
Reindexing seemes to have fixed the problem. I'll let you know if it continues.