In many places we display optime in decimal (e.g. in rs.status()), but elsewhere the 'seconds' part of the optime is displayed in hex, which can make debugging a bit inconvenient. e.g. the following message string (also in rs.status())

"lastHeartbeatMessage" : "still syncing, not yet to minValid optime 53b2817e:349",

It would be good if OpTime::toString() could be changed to print the time in decimal.