memory leak on ~QFile()

I've got a memory leak show by Valgrind, when I try to delete a pointer that first I create like this:

QString qxmlFile (strPathConfiguracion.c_str());
QFile *xmlFile = new QFile(qxmlFile);
xmlFile->open(QIODevice::ReadOnly);
xmlFile->close();
delete xmlFile;

and I've got the next result by valgrind.

120 bytes in 1 blocks are still reachable in loss record 5,745 of 7,447
==4942== at 0x4C27CC1: operator new(unsigned long) (vg_replace_malloc.c:261)
==4942== by 0xCB7FAA2: QMutex::QMutex(QMutex::RecursionMode) (in /usr/lib/libQtCore.so.4.6.2)
==4942== by 0xCB80EE2: QMutexPool::get(void const*) (in /usr/lib/libQtCore.so.4.6.2)
==4942== by 0xCC8E822: QObject::~QObject() (in /usr/lib/libQtCore.so.4.6.2)
==4942== by 0xCC06AD2: QFile::~QFile() (in /usr/lib/libQtCore.so.4.6.2)
==4942== by 0x15379F1: Iberdrola::MRR::General::Configuracion::CBaseConfiguracion::ValidarXml(std::string) (CBaseConfiguracion.cpp:270)

If this is something that I do wrong, please let me know, but I think that is simple and it's right.