Um... well it's definitely a concern. I would say that you might stick to state schools where you don't have to submit your subject score, at least in order to acquire your Master's. Of course, if it is a concern for you, and settling for a lesser institution (and uncertainty in your future admissions prospects), then you might consider retaking it and trying again next year. Take some advanced coursework as a guest student at a local university, and perhaps take some courses in a related field (Computer Science, Physics, etc.) or a language, and prepare, prepare, prepare to retake it.
Think about what adcoms must consider--you either didn't prepare for the test, you don't know the material (I'm not saying this, this is just how it appears) as well as 55% of your peers, or you were just having a bad day (I'll assume the latter). You are applying to potentially obtain a fellowship that would pay you to teach these subjects to undergraduate students; the GRE mainly consists of rather basic material, with a handful of questions from more advanced topics. Grab the Princeton Review book, some Schaum's Outlines, and dust off some of those old undergraduate textbooks and work through the problems. Take it again, and you should be set.
Best of luck in the future!