That’s pretty young.
My first thought as well
44 men have been President (I'm counting Cleveland only once). 5 of them are still alive so 39 have died. Of the 39, 14 were younger than 66 when they died (4 of those because they were assassinated), and another 5 were in the 66 to 68 year range when they died. The median age at death for those who are deceased is 70. (Four of the five living Presidents are past 70 now so the median will rise.) That is better than the average life expectancy was for most of American history, but most Presidents were past their 50th birthday when they first took office.