Keane Ng from Google, the YouTube community manager, announced in a YouTube Help thread that the view counts on your channel page may have dropped due to a change on how Google counts YouTube views on that page.
From now on, only public video views will be counted and represented in the view count on your YouTube page. Views for private, unlisted or previously deleted videos will no longer count on that page. If you have removed very popular videos from your channel and want those views to count, you can mark them as public again (assuming you did not delete the video) and the views should begin counting again.
Your YouTube Analytics are unaffected by this change.
As of last night you may have noticed a drop on the views counted on your channel pages. This is because the views shown on your channel now only include views from public videos, and not private, unlisted or previously deleted videos. Over the past few weeks we've been removing views for deleted videos, after which we've started removing views for private and unlisted videos.
To include views from private or unlisted videos, change them to 'public' and the views will be counted again within 24 hours.
YouTube Analytics channel view counts will continue to include views from all videos that were public at the time the view occurred even if the videos are now private, unlisted, or deleted.
Forum discussion at YouTube Help.