In Squeak 3.7a 5707,

Date year: 2004 month: 2 day: 30

returns a Date object representing March .

In 3.6 this would have been an error.

I don't think it's useful here to try to silently "do what I mean" - 
the input is probably invalid because of user error (for example, 
switching the values for day and month).  This needs to be caught.