I have a computer science degree, should I read a few engineering books and sell myself as an electrical engineer? Maybe if I dabble with stuff picked up at the Radio Shack fire sale first?
Most computer scientists that I have come across hate the code generated by most electrical engineers. There are damn few exceptions. EEs tend to think "if it works, it's right" and then proceed to generate hideous code that is impossible to maintain (but it ran for their test cases, next problem). The only exception that I know of is an EE I work with that has absolutely no ego involved and asks for design and coding help at the proper junctures. Over the last ten years he's effectively been given a course in CS.
So, please, no. Just because you can rub a few lines of code together, don't consider yourself a professional software developer. I applaud the interviewers for delving into CS theory and rejecting you because of your lack of knowledge on your chosen field.