One of our production secondary databases now has an optime that is nearly 24 hours old. Looking at the logs at that optime I see some assertions

[rsSync] Assertion: 10334:Invalid BSONObj size: 1818322244 (0x4465616C) first element: r: ?type=101; TraceSource 'WaWorkerHost.exe' event"
[rsSync] replSet syncTail: 10334 Invalid BSONObj size: 1818322244 (0x4465616C) first element: r: ?type=101, syncing: { ts: Timestamp 1345750316000|66, h: 1018104994802725908, op: ""u"", ns: ""xq.SessionModel"", o2:

{ _id: ""fOLao2S5-cu8sYYVWuAmOr_t77XseH8rN0t7nt-fNUI"" }

, o:

{ _id: ""fOLao2S5-cu8sYYVWuAmOr_t77XseH8rN0t7nt-fNUI"", Expires: new Date(1345752117253), Id: ""damcomm"", AccountId: BinData, Roles: [ ""Dealer"" ], AuthApiToken: null }

}; TraceSource 'WaWorkerHost.exe' event"
[rsSync] replSet not trying to sync from 10.26.10.41:27017, it is vetoed for 269 more seconds; TraceSource 'WaWorkerHost.exe' event"
[rsSync] replSet syncing to: 10.26.2.151:27017; TraceSource 'WaWorkerHost.exe' event"
[rsSync] Assertion: 10334:Invalid BSONObj size: 1818322244 (0x4465616C) first element: r: ?type=101; TraceSource 'WaWorkerHost.exe' event"
[rsSync] replSet syncTail: 10334 Invalid BSONObj size: 1818322244 (0x4465616C) first element: r: ?type=101, syncing: { ts: Timestamp 1345750316000|66, h: 1018104994802725908, op: ""u"", ns: ""xq.SessionModel"", o2:

{ _id: ""fOLao2S5-cu8sYYVWuAmOr_t77XseH8rN0t7nt-fNUI"" }

, o:

{ _id: ""fOLao2S5-cu8sYYVWuAmOr_t77XseH8rN0t7nt-fNUI"", Expires: new Date(1345752117253), Id: ""damcomm"", AccountId: BinData, Roles: [ ""Dealer"" ], AuthApiToken: null }

}; TraceSource 'WaWorkerHost.exe' event"
[rsSync] replSet not trying to sync from 10.26.10.41:27017, it is vetoed for 238 more seconds; TraceSource 'WaWorkerHost.exe' event"
[rsSync] replSet not trying to sync from 10.26.2.151:27017, it is vetoed for 269 more seconds; TraceSource 'WaWorkerHost.exe' event"