vmx0: watchdog timeout on queue 2, no interrupts on BSP

Recently we experienced a strange problem.
We noticed a lot of these messages in the logs:
vmx0: watchdog timeout on queue 2
(always queue 2)
Also, we noticed that connections to some end points did not work at all
while others worked without problems.  I assume that that was because
specific flows got assigned to that queue 2.

Further investigation has shown that none of interrupts assigned to the
BSP has ever fired (since boot, of course).  That included vmx0:rx2 and
vmx0:tx2.  But also interrupts for other drivers as well.

Trying to get more information I rebooted the system and the problem
disappeared.

Has anyone seen anything like that?
Any thoughts on possible causes?
Any suggestions what to check if/when the problem reoccurs?

Thanks!
-- 
Andriy Gapon