The meta protons should show up as a doublet of doublets, actually. This is because it will be split by two inequivalent protons (the ortho and the para) It turns out that the meta-ortho coupling is almost the same as the meta-para coupling, so I guess that you just can't make out the smaller splitting with the resolution of the spectrum you have. When this happens, it is usually referred to as an "apparent triplet," that is, it looks like a triplet, but it really shouldn't be.
I hope this helps.