When you are Mr. Prose, and it's your birthday, it's really not a big deal. When you are Mr. Prose and it's your 40th birthday, it's still really not a big deal. Andy has made it very clear that there was to be no party - definitely not a single surprise - no gifts, and nothing special. To him, it's just another day and another decade. Fortunately for the Mr., he has a Mrs. who understands the importance of big deals. (but also respects her husband's wishes and makes the big deal really only medium sized...)
There were homemade cards and 40 gifts - yes, forty. And a gin and tonic in the shower and sushi after the Littles went to bed.