Vacuum freeze help

Hello,
I have a postgresql 9.5.4 cluster and was testing with vacuum freeze. I expected the value of xmin to be set to '2' when I vacuum a particular table with the VACUUM FREEZE command. But for some reason this doesn't happen. Here is my small test:
test=# create table t1 (col1 int, col2 int);CREATE TABLEtest=# insert into t1 values (1,2), (3,4);INSERT 0 2test=# select xmin, xmax, * from t1; xmin | xmax | col1 | col2 ------+------+------+------ 1845 |    0 |    1 |    2 1845 |    0 |    3 |    4(2 rows)
test=# vacuum freeze t1;VACUUMtest=# select xmin, xmax, * from t1; xmin | xmax | col1 | col2 ------+------+------+------ 1845 |    0 |    1 |    2 1845 |    0 |    3 |    4(2 rows) As you can see from the results of the last select statement the value of xmin is 1845 instead of 2 which I expected it to be. On my 9.0 cluster this works fine. Has this behavior of postgresql been changed since 9.0? Can anyone explain this?

Ben.