Two of the memorials detail ' a regretted wife' and another details the date of death as '30.2.1540'.
The Gregorian Calender was not brought into use until 1582. This is the calender, with some amendments, that we use today. Prior to 1582 the Julian (after Julius Caesar) Calender was in general use throughout Europe, usually by the Church but local variations were put in to make up the odd days that this calender missed out of the year. Sometimes as many as 21 days would be added, usually during February.
Don't you just lurve pedantry.