This behavior is by design and should be expected.
On the slave core, for the replicated agent you should expect to see an orphaned recovery point for the very first recovery point in the chain. This is because replication had been allowed to resume so the very next recovery point after the seed was created) was picked up and replicated to the remote core, thereby it has been displaced from its recovery chain.
As soon as the seed drive has been consumed on the remote core, the orphaned recovery point will return to a normal recovery point since it will then be paired with its recovery chain when the data is copied over to the repository where the replicated agent resides.
If replication was still paused, then once the seed drive was consumed and replication resumed, then you should not expect to see any orphaned recovery point when the data has been allowed to fully replicate going forward until the next time you seed again.