shot scare!

I'm 19 weeks pregnant and I got the flu shot yesterday. My military doc gave it to me without guidance from my ob but in this job there's not much to do to get out of stuff like that. Of course the first thing I see this morning is a post advising women not to get the flu shot until at least 23 weeks.Is this something I should be concerned about? Any success stories with flu shots so early in pregnancy?