Seen with default (3.4.0) framework builds on OS X 10.9 with ActiveTcl 8.5.15.0:

./configure --enable-universalsdk=/ --with-universal-archs=intel --enable-framework=/tmp/t/Library/Frameworks
make && make install
cd /tmp/t
/tmp/t/bin/python3.4 -m test -w -uall
[...]
[343/389/1] test_ttk_guionly
can't invoke "event" command:  application has been destroyed
    while executing
"event generate $w <<ThemeChanged>>"
    (procedure "ttk::ThemeChanged" line 6)
    invoked from within
"ttk::ThemeChanged"
can't invoke "event" command:  application has been destroyed
    while executing
"event generate $w <<ThemeChanged>>"
    (procedure "ttk::ThemeChanged" line 6)
    invoked from within
"ttk::ThemeChanged"
can't invoke "event" command:  application has been destroyed
    while executing
"event generate $w <<ThemeChanged>>"
    (procedure "ttk::ThemeChanged" line 6)
    invoked from within
"ttk::ThemeChanged"
can't invoke "event" command:  application has been destroyed
    while executing
"event generate $w <<ThemeChanged>>"
    (procedure "ttk::ThemeChanged" line 6)
    invoked from within
"ttk::ThemeChanged"
[344/389/1] test_ttk_textonly
[...]

When running test_ttk_guionly by itself (or in combination with a few neighboring tests):

  /tmp/t/bin/python3.4 -m test -w -uall test_ttk_guionly

the message is not seen.  I had not seen this behavior prior to somewhere in the 3.4.0 development cycle.