A question about sequences and backup/restore cycles

I typically design a system with primary keys defined, like this:

CREATE TABLE employee (
employee_key integer DEFAULT nextval('employee_key_serial')
PRIMARY KEY ,

I use scripts to build the database structures and load the data. I am
careful to get the dependencies in the correct order, so that the keys later
structures depend on already exist.

Today I was going over the design for the current project with a friend,
whose expertise i respect. he said that he had issues on a system designed
by an OEM that had dependencies on keys developed from sequences after a
backup/restore cycle,

Will I potentially have these issues? If so, what can I do different to
avoid this being an issue?

--
"They that would give up essential liberty for temporary safety deserve
neither liberty nor safety."
-- Benjamin Franklin