error when i run nodejs on EC2

After I git clone my app onto EC2 and run it with the following command:

nohup nodejs app.js &

I get the following error:

[Error: /home/ubuntu/bluesky-scheduler2/node_modules/agenda/node_modules/mongodb/node_modules/bson/build/Release/bson.node: invalid ELF header]
js-bson: Failed to load c++ bson extension, using pure JS version
[Error: /home/ubuntu/bluesky-scheduler2/node_modules/mongodb/node_modules/bson/build/Release/bson.node: invalid ELF header]
js-bson: Failed to load c++ bson extension, using pure JS version

The app runs fine but what do I need to do to remove these errors?