Meteor app on Heroku fails over time -

i host meteor app on heroku mongolab add on (all free plans). on time, app fail. not able login (using account package), keep getting internal server error response, no other helpful messages. fix need restart dyno heroku ps:restart.

but on server side these errors logged

2013-05-10 01:27:13.530748+00:00 app web.1 - - exception in queued task: error: failed connect [xxx.mongolab.com:41357] @ object.future.wait (/app/.meteor/local/build/server/node_modules/fibers/future.js:322:15) @ _.extend._nextobject (app/packages/mongo-livedata/mongo_driver.js:485:47) @ _.extend.foreach (app/packages/mongo-livedata/mongo_driver.js:506:22) @ _.extend.getrawobjects (app/packages/mongo-livedata/mongo_driver.js:550:12) @ _.extend._pollmongo (app/packages/mongo-livedata/mongo_driver.js:821:46) @ object._.extend._unthrottledensurepollisscheduled [as task] (app/packages/mongo-livedata/mongo_driver.js:765:12) @ _.extend._run (app/packages/meteor/fiber_helpers.js:126:18) @ _.extend._schedulerun (app/packages/meteor/fiber_helpers.js:104:14) except 2013-05-10 01:27:13.530748+00:00 app web.1 - - - - - - - heroku/auction-app 2013-05-10 01:27:13.531106+00:00 app web.1 - - @ server.connect.connectionpool.on.server._serverstate (/app/.meteor/local/build/server/node_modules/mongodb/lib/mongodb/connection/server.js:564:74) 2013-05-10 01:27:13.531106+00:00 app web.1 - - @ eventemitter.emit (events.js:126:20) 2013-05-10 01:27:13.531106+00:00 app web.1 - - @ connection.on._self._poolstate (/app/.meteor/local/build/server/node_modules/mongodb/lib/mongodb/connection/connection_pool.js:124:15) 2013-05-10 01:27:13.531106+00:00 app web.1 - - @ eventemitter.emit (events.js:99:17) 2013-05-10 01:27:13.531106+00:00 app web.1 - - @ socket.errorhandler (/app/.meteor/local/build/server/node_modules/mongodb/lib/mongodb/connection/connection.js:465:10) 2013-05-10 01:27:13.531106+00:00 app web.1 - - @ socket.eventemitter.emit (events.js:96:17) 2013-05-10 01:27:13.531106+00:00 app web.1 - - @ socket._destroy.self.erroremitted (net.js:329:14) 2013-05-10 01:27:13.531106+00:00 app web.1 - - @ process.startup.processnexttick.process._tickcallback (node.js:244:9) 2013-05-10 01:27:13.531106+00:00 app web.1 - - @ server.connect.connectionpool.on.server._serverstate (/app/.meteor/local/build/server/node_modules/mongodb/lib/mongodb/connection/server.js:564:74) heroku/auction-app context 2013-05-10 01:27:13.531106+00:00 app web.1 - - @ eventemitter.emit (events.js:126:20) heroku/auction-app context 2013-05-10 01:27:13.531106+00:00 app web.1 - - @ connection.on._self._poolstate (/app/.meteor/local/build/server/node_modules/mongodb/lib/mongodb/connection/connection_pool.js:124:15) heroku/auction-app context 2013-05-10 01:27:13.531106+00:00 app web.1 - - @ eventemitter.emit (events.js:99:17) heroku/auction-app context 2013-05-10 01:27:13.531106+00:00 app web.1 - - @ socket.errorhandler (/app/.meteor/local/build/server/node_modules/mongodb/lib/mongodb/connection/connection.js:465:10) heroku/auction-app context 2013-05-10 01:27:13.531106+00:00 app web.1 - - @ socket.eventemitter.emit (events.js:96:17) heroku/auction-app context 2013-05-10 01:27:13.531106+00:00 app web.1 - - @ socket._destroy.self.erroremitted (net.js:329:14) heroku/auction-app context 2013-05-10 01:27:13.531106+00:00 app web.1 - - @ process.startup.processnexttick.process._tickcallback (node.js:244:9) heroku/auction-app 

seems error due failure connect databse. doesn't explain why have restart app, not database (over @ mongolab).