There were no blood moons in 1948.
This is where the experts "fudge" a little bit.
The blood moons were 1949-1950.
The reason 1948 is referenced so often is Israel's declared statehood in May 1948. But this was 11 months before the April blood moon of 1949.
(So God is off by a year in His calculations?)
Good question. Maybe they are throwing a bit of a fudge factor.