I don't have a solution, but I have a diagnosis, and the next step. If multiple files, some long, some short, are fetching 82KB, then double check that you are fetching the correct URL.
It looks like, when the user chooses a filename you aren't fetching the correct URL, but something returning 82KB of data, like the directory listing.
You can check by running the DrEdit sample app from https://developers.google.com/drive/examples/objectivec and by turning on GMHTTPFetcher logging, (GMHTTPFetcher is a wrapper for NSURLConnection) http://code.google.com/p/gtm-http-fetcher/wiki/GTMHTTPFetcherIntroduction#HTTP_Logging