I think I might have found a micro bug in SQL Server 2005 Management Studio.
Whilst doing some design tweaks in a Data warehouse to make it match reality instead of the third party spec I noticed that a number of fields that I had changed the data type and length of were the right data type but had the default length.
E.g. I typed Varchar(10) but I got Varchar(50).
It seems that if you type the data type then the first time you move focus it reverts to the default length. If you then go back and change the length it is quite happy.