proftpd mod_shaper bug?

% lsof -p 11508  | grep shaper
proftpd 11508 nobody  mem    REG      253,0    77410   1402491 /usr/libexec/proftpd/mod_shaper.so
proftpd 11508 nobody    4w   REG      253,0     4163   1402473 /var/log/ftpd/shaper.log
proftpd 11508 nobody    5u   REG      253,0      120   1402472 /var/log/ftpd/shaper.tab
% cd /var/log/ftpd
% mv shaper.log shaper.log.old
% touch shaper.log
% cat /var/run/proftpd.pid
11508
% kill -HUP 11508
% lsof -p 11508 | grep shaper
proftpd 11508 nobody  mem    REG      253,0    77410   1402491 /usr/libexec/proftpd/mod_shaper.so
proftpd 11508 nobody    1u   REG      253,0      240   1402472 /var/log/ftpd/shaper.tab
proftpd 11508 nobody    4w   REG      253,0    39864   1402473 /var/log/ftpd/shaper.log.old
proftpd 11508 nobody    5u   REG      253,0      240   1402472 /var/log/ftpd/shaper.tab
%% vim /etc/logrotate.d/proftpd
% proftpd  -V
Compile-time Settings:
  Version: 1.3.5 (stable)
  Platform: LINUX [Linux 2.6.18-348.16.1.el5PAE i686]
  Built: Tue Jun 10 2014 20:04:55 BST
  Built With:
    configure  '--host=i686-redhat-linux-gnu' '--build=i686-redhat-linux-gnu' '--target=i386-redhat-linux' '--program-prefix=' '--prefix=/usr' '--exec-prefix=/usr' '--bindir=/usr/bin' '--sbindir=/usr/sbin' '--sysconfdir=/etc' '--datadir=/usr/share' '--includedir=/usr/include' '--libdir=/usr/lib' '--libexecdir=/usr/libexec' '--localstatedir=/var' '--sharedstatedir=/usr/com' '--mandir=/usr/share/man' '--infodir=/usr/share/info' '--libexecdir=/usr/libexec/proftpd' '--localstatedir=/var/run/proftpd' '--disable-strip' '--enable-ctrls' '--enable-dso' '--enable-facl' '--enable-ipv6' '--enable-nls' '--enable-shadow' '--with-lastlog' '--with-libraries=/usr/lib/mysql' '--with-includes=/usr/include/mysql' '--with-pkgconfig=lib/pkgconfig' '--with-shared=mod_auth_pam:mod_ban:mod_ctrls_admin:mod_exec:mod_facl:mod_load:mod_quotatab:mod_quotatab_file:mod_quotatab_radius:mod_quotatab_sql:mod_radius:mod_ratio:mod_readme:mod_rewrite:mod_shaper:mod_site_misc:mod_sql:mod_wrap2:mod_wrap2_file:mod_wrap2_sql:mod_sql_postgres:mod_ifsession' 'build_alias=i686-redhat-linux-gnu' 'host_alias=i686-redhat-linux-gnu' 'target_alias=i386-redhat-linux' 'CFLAGS=-O2 -g -m32 -march=i386 -mtune=generic -fasynchronous-unwind-tables' 'CXXFLAGS=-O2 -g -m32 -march=i386 -mtune=generic -fasynchronous-unwind-tables'

  CFLAGS: -O2 -g -m32 -march=i386 -mtune=generic -fasynchronous-unwind-tables -Wall
  LDFLAGS: -L$(top_srcdir)/lib  -L/usr/lib/mysql -L/usr/lib
  LIBS: -lacl  -lcap -lsupp -lcrypt -ldl

  Files:
    Configuration File:
      /etc/proftpd.conf
    Pid File:
      /var/run/proftpd/proftpd.pid
    Scoreboard File:
      /var/run/proftpd/proftpd.scoreboard
    Header Directory:
      /usr/include/proftpd
    Shared Module Directory:
      /usr/libexec/proftpd

  Features:
    - Autoshadow support
    + Controls support
    + curses support
    - Developer support
    + DSO support
    + IPv6 support
    + Largefile support
    + Lastlog support
    - Memcache support
    + ncursesw support
    + NLS support
    - OpenSSL support
    - PCRE support
    + POSIX ACL support
    + Shadow file support
    + Sendfile support
    + Trace support

  Tunable Options:
    PR_TUNABLE_BUFFER_SIZE = 1024
    PR_TUNABLE_DEFAULT_RCVBUFSZ = 8192
    PR_TUNABLE_DEFAULT_SNDBUFSZ = 8192
    PR_TUNABLE_GLOBBING_MAX_MATCHES = 100000
    PR_TUNABLE_GLOBBING_MAX_RECURSION = 8
    PR_TUNABLE_HASH_TABLE_SIZE = 40
    PR_TUNABLE_NEW_POOL_SIZE = 512
    PR_TUNABLE_SCOREBOARD_BUFFER_SIZE = 80
    PR_TUNABLE_SCOREBOARD_SCRUB_TIMER = 30
    PR_TUNABLE_SELECT_TIMEOUT = 30
    PR_TUNABLE_TIMEOUTIDENT = 10
    PR_TUNABLE_TIMEOUTIDLE = 600
    PR_TUNABLE_TIMEOUTLINGER = 30
    PR_TUNABLE_TIMEOUTLOGIN = 300
    PR_TUNABLE_TIMEOUTNOXFER = 300
    PR_TUNABLE_TIMEOUTSTALLED = 3600
    PR_TUNABLE_XFER_SCOREBOARD_UPDATES = 10

%