can i retrieve an array stored in postgresql via sequel as an array?

This is usually handled when you load the pg_array extension into your Sequel::Database instance. Maybe you just loaded the pg_array extension file without loading it into your Sequel::Database instance. You might have done:

Sequel.extension :pg_array

instead of:

DB.extension :pg_array

You need to load the pg_array extension into your Sequel::Database instance for retrieved values to be array-like objects and not strings.