A problem with alq module!

[Computer Network Man]

Dear Guys;
In a fresh FreeBSD 9 or 9.1 Release if you just run these commands:
# kldload alq
# kldunload alq
# init 0 or shutdown -p now
it will panic!
maybe it's a bug.
We have a module which uses alq API's.
    MODULE_DEPEND(mymodule, alq, 1, 1, 1)
when our module starts, loads alq. and when it stops, unloads alq. So after
starting and stoping our module and shutdown, we have panic.
any opinion in this regard would be appreciated.