It is supposed to be that way.
From the QT documentation:
"Qt is built using the -MD(d) switch, which links against the dynamic C/C++ runtime libraries. This is necessary as we have experienced memory problems when using anything but the -MD(d) flag, and in general, it is recommended to use. You should not alter this flag yourself for your application, because it conflicts with how the Qt library is built if you change the flag to -MT. You should not change it for Qt either, since it is likely to cause problems"
More info can be found here:
http://qt-project.org/faq/answer/why_does_a_statically_built_qt_use_the_dynamic_visual_studio_runtime_librar