well, it could be just the character of the yeast (i've never used it), but normally i wouldn't pitch a pack that hasn't swelled.
as always, in the future you should make a starter and keep dry yeast on hand just in case
all you can do now is wait and see. worse case scenario, you just introduced some bad yeast or bacteria to your brew due to a contaminated pack of yeast (don't worry, it's VERY unlikely).
another thing that might happen is the yeast doesn't work and you'll have to pitch some more yeast.
i'd wait a day or two before you do anything, she'll probably just start bubbling away!