I've found that place/nearby and place/list both seem to need to be POST requests in order to work. The docs list both as GET requests. Would you say it makes the most sense to just make all my API calls POST?
Now that you mention it, I thought I was by setting the $args parameter on the get calls, but now realize the php sdk only adds the args array for POST requests. Sorry, I'd assumed it might be using http_build_query for GET requests (which would keep the api consistent). I'll fork and add it.