I personally think this is being overly picky, but as long as you make it clear that you only accept resumes in these formats there is no problem. I once sent a cold job application to a company that had no resume format requirement on its career page. I sent my resume in .doc. I could have sent it in PDF or something else, but in my experience most companies prefer to receive resumes in .doc unless otherwise stated. This company also sells a product for Windows (and other platforms) so I expected it to use Word internally. A few months later I found a job ad from them on Monster where they very clearly stated that they would only accept resumes in PDF. To this day their career page still does not specify a file format preference for resumes.
Yeah, it's somewhat frustrating how some people will screen you for sending a .DOC, and some people will screen you for NOT sending a .DOC. For extra fun, let's ask whether we should wear a suit to the interview: must wear for consideration, or immediate disqualification/no-hire? There's disagreement there as well.
The only safe advice is to ask ahead of time; unfortunately for you, there was no one to ask. Dysfunction is unfortunately common.
I personally think this is being overly picky, but as long as you make it clear that you only accept resumes in these formats there is no problem. I once sent a cold job application to a company that had no resume format requirement on its career page. I sent my resume in .doc. I could have sent it in PDF or something else, but in my experience most companies prefer to receive resumes in .doc unless otherwise stated. This company also sells a product for Windows (and other platforms) so I expected it to use Word internally. A few months later I found a job ad from them on Monster where they very clearly stated that they would only accept resumes in PDF. To this day their career page still does not specify a file format preference for resumes.