More than that, it is common to see the "0 indexed" message for a new sitemap submission. There seems to be a reporting lag before the crawl of the sitemap shows up in Webmaster Tools.
I have seen that reporting lag as well. I manually submitted one of my sitemaps recently after I had corrected an error in it. It showed up with 0 pages indexed for about a day before the real number of pages indexed was shown in webmaster tools.