expdp/impdp migration has changed storage clauses?

 Hi,
after migrating a fair amouot of schemes with expdp from 10.2.0.4.4 (Solaris Sparc) and then impdp them into 10.2.0.5.0 (x86-64), I notice that many objects (tables and indexes) have hade their storage clause changed, from:

STORAGE    (
            INITIAL          64K

            MINEXTENTS       1
            MAXEXTENTS       UNLIMITED
            PCTINCREASE      0
            BUFFER_POOL      DEFAULT
           )


STORAGE    (
            INITIAL          64K
            NEXT             1M
            MINEXTENTS       1
            MAXEXTENTS       UNLIMITED
            PCTINCREASE      0
            BUFFER_POOL      DEFAULT
           )

Note the added "Next 1M" on the new objects.

How come this have changed? 
How could this affect performance? (I'm by no way an expert in the tuning area, so please bear with me )
Anything else that I should think about in this situation?