[tor-relays] Directory traffic

[Jobiwan Kenobi]

As of between 18:00 and 19:00 yesterday (9/30/13) directory traffic on 
my relay has gone up dramatically, from mere background noise to more 
than half my advertised bandwidth, and hasn't really come down since. 

I pasted the numbers from /opt/var/lib/tor/state into a spreadsheet 
and made a graph. The green line is the interesting one. I don't know 
whether I can send attachments to the list, so I put it here: 
http://jb4m.homeip.net/T/graph1-dirw.png 

Right now, I advertise 1 Mbit but don't actually limit bandwidth, 
and I was quite happy with the profile until this started. 
If it keeps doing this, I may have to put a cap on again. 
I'm a non-exit, non-guard.

Is this normal?
Is there anything I should look into?

Thanks,
-Job