If the viewport is offset from the map, anything drawn in an object will be equally offset from that object.

Here the viewport is offset 32px to the right:
http://greghoustondesign.com/sandbox/game-issue/index.html

Note in the bottom right corner that the text and their objects are no longer aligned. The text is 32px to the right.

Scroll down to the bottom right of the page. Add a couple enemies. Note that their health bars are no longer centered above them.

Click on the blue tower icon, then click on an empty space in the map. Click on the new tower. Note that the prices below the "Sell" and "Upgrade" icons are offset.

Someone else who ran into this issue.
https://groups.google.com/forum/?fromgroups=#!topic/melonjs/ueUtLkh79Vc