Looks as if primary is inside the container on the offending page. There is probably a closing div either not present or entered at the wrong place. If you used a shortcode to enter the calendar probably an error there.
@Martin — That was it. I had some comments in there to remind me of some configuration options that must have included some offending code. I’ve reproduced them below for your review. Are parentheses not allowed in comments? Anything else stand out to you? I’ll leave the comments out if I need to — that fixes my offending div problem — but if you see something wrong here I’d appreciate the insight.
<!-- To display Sugar Event Calendar, add shortcode (open bracket)sc_events_calendar(close bracket) -->
<!-- To display Constant Contact Calendar, add shortcode (open bracket)eventspot(close bracket) -->
<!-- Event shortcode options
'id' => null, // Show a specific event; enter Event ID (found on the Events page) to use
'limit' => 3, // Number of events to show by default
'showdescription' => true, // Show event Description
'datetime' => true, // Show event Date & Time
'location' => false, // Show event Location
'map' => false, // Show map link for Location (if Location is shown)
'calendar' => false, // Show "Add to Calendar" link
'directtoregistration' => false, // Link directly to registration page, rather than event homepage
'newwindow' => false, // Open event links in a new window