MongoDB thinks it's running a replica? - mongodb

Question

I'm running MongoDB (version 2.4) behind a Django application served by Apache.
In the past few days, I'm seeing the following error come up many times an hour in the Apache logs, on all sorts of different requests:
AutoReconnect: not master and slaveOk=false
I did not explicitly create a replica, and to the best of my knowledge am not running one. rs.status() says that we are not running with --replset.
Mongo is run with:
'mongod --dbpath /srv/db/mongodb/ --fork --logpath /var/log/mongodb.log --logappend --auth'
There is one mongod process running on the server.
What's going on here?
Edit -
Here's the tail end of the stack trace, as requested.
File "/var/www/sefaria_dev/sefaria/texts.py", line 916, in parse_ref
shorthand = db.index.find_one({"maps": {"$elemMatch": {"from": pRef["book"]}}})
File "/usr/local/lib/python2.7/dist-packages/pymongo/collection.py", line 604, in find_one
for result in self.find(spec_or_id, *args, **kwargs).limit(-1):
File "/usr/local/lib/python2.7/dist-packages/pymongo/cursor.py", line 904, in next
if len(self.__data) or self._refresh():
File "/usr/local/lib/python2.7/dist-packages/pymongo/cursor.py", line 848, in _refresh
self.__uuid_subtype))
File "/usr/local/lib/python2.7/dist-packages/pymongo/cursor.py", line 800, in __send_message
self.__uuid_subtype)
File "/usr/local/lib/python2.7/dist-packages/pymongo/helpers.py", line 98, in _unpack_response
raise AutoReconnect(error_object["$err"])
AutoReconnect: not master and slaveOk=false
rs.status() returns:
{
"ok" : 0,
"errmsg" : "not running with --replSet"
}
rs.conf() returns null.
I haven't seen an indication of error in the mongodb.log that corresponds to one of the apache.log errors.