You mean if it's possible that the Cluster state (as represented to peers by Raft) changed -by adding a new pin to it-, but the pinned content did not arrive to the peers on which it's pinned? Yes it's possible. Cluster only asks IPFS peers to pin. Finding and fetching this content is IPFS's task.
Understand that while, internally, Raft is a log of entries, the external view of this is just a map from [cid]->PinInformation
that is the same in all cluster peers. The Raft state (or shared state is what
ipfs-cluster-ctl pin ls shows).
If you didn't see it, there is some information here: https://cluster.ipfs.io/documentation/internals/