The DayPilotBubble doesn't work well with the traditional scheduler theme. It calculates the correct size and position, animates into view, and then immediately stretches to be 250px high.
This can be reproduced on your "silver theme" page:
http://www.daypilot.org/demo/Scheduler/ThemeSilver.aspx
I've reproduced the problem in Firefox 21, Chrome 29 and IE10.
Turning off animation appears to be the only workaround.