Possible memory leak in zmq::msg_t

#include "czmq.h"

int main(int argc, char* argv[])
{
    const char* endpoint = "inproc://test";
    const char* msg = "Hello Hello Hello Hello Hello!";  // length 30

    // create context
    zctx_t* ctx = zctx_new();
    assert(ctx);

    // create and bind pull socket
    void* pull = zsocket_new(ctx, ZMQ_PULL);
    int port = zsocket_bind(pull, endpoint);

    // create and connect push socket
    void* push = zsocket_new(ctx, ZMQ_PUSH);
    int rc = zsocket_connect(push, endpoint);
    assert(rc == 0);

    // destroy puller, then send
    zsocket_destroy(ctx, pull);
    sleep(1);
    rc = zsocket_sendmem(push, msg, strlen(msg), ZFRAME_DONTWAIT);
    assert(rc == -1);

    // clean up
    zsocket_destroy(ctx, push);
    zctx_destroy(&ctx);
}

/*
Output:

# valgrind --leak-check=full --show-reachable=yes ./testcase
==4354== Memcheck, a memory error detector
==4354== Copyright (C) 2002-2012, and GNU GPL'd, by Julian Seward et al.
==4354== Using Valgrind-3.8.1 and LibVEX; rerun with -h for copyright info
==4354== Command: ./testcase
==4354==
==4354==
==4354== HEAP SUMMARY:
==4354==     in use at exit: 70 bytes in 1 blocks
==4354==   total heap usage: 66 allocs, 65 frees, 40,842 bytes allocated
==4354==
==4354== 70 bytes in 1 blocks are definitely lost in loss record 1 of 1
==4354==    at 0x4C277AB: malloc (in /usr/lib64/valgrind/vgpreload_memcheck-amd64-linux.so)
==4354==    by 0x5098850: zmq::msg_t::init_size(unsigned long) (msg.cpp:60)
==4354==    by 0x4E5212B: zsocket_sendmem (zsocket.c:211)
==4354==    by 0x400B19: main (in /root/zeromq/testcase)
==4354==
==4354== LEAK SUMMARY:
==4354==    definitely lost: 70 bytes in 1 blocks
==4354==    indirectly lost: 0 bytes in 0 blocks
==4354==      possibly lost: 0 bytes in 0 blocks
==4354==    still reachable: 0 bytes in 0 blocks
==4354==         suppressed: 0 bytes in 0 blocks
==4354==
==4354== For counts of detected and suppressed errors, rerun with: -v
==4354== ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 2 from 2)
*/