"The term to search must be a string" when using the rest search api


I’m using the rest API, get’ing to /search/tweets.json with the below parameters.
Earlier today this query (well a much more complex one) was working fine.
Now I’m receiving the string Error: The term to search must be a string back from the API.

A google and search of the forum for this error finds no one else mentioning it, does anyone have any idea what the cause is? To check the obvious, yes q is a string!

My full post data looks like: q=weather%20OR%20sunny&lang=en&result_type=recent&include_entities=false&count=100

Which as a javscript object is:
{ q: ‘weather OR sunny’,
lang: ‘en’,
result_type: ‘recent’,
f: ‘realtime’,
include_entities: ‘false’,
count: 100 }