Bootstrap 3.1.0 modal sizing not applied

After updating my `bootstrap-sass` gem to `3.1.0` to take advantage of the new sizing options on modals (`.modal-lg` and `.modal-sm`), I've been unable to get the styling to be applied. My code is as follows: ``` <div aria-hidden="false" aria-labeldby="ccModalLabel" class="modal fade in" id="ccModal" role="dialog" style="display: block;"> <div class="modal-dialog modal-sm"> ...content... </div> </div> ``` Which, as far as I can tell, is nearly identical to the example in all the attributes that matter: ``` <div class="modal fade bs-modal-sm" tabindex="-1" role="dialog" aria-labelledby="mySmallModalLabel" aria-hidden="true"> <div class="modal-dialog modal-sm"> <div class="modal-content"> ... </div> </div> </div> ``` However, upon inspection, the `modal-sm` class isn't been evaluated in my code as it is in the example, leading me to think that maybe it isn't included in the gem somehow, or am I missing something? The modal works in every other way aside the sizing.