Can an unconfirmed transaction fall under the radar?
It's not a rare event. It's the nature of the network that not all transactions will reach all nodes. There's also the possibility that some nodes have heard of the transaction but then dropped it from their mempool when they encountered higher fee transactions. They do this to prevent DDoS attacks because memory is a scarce resource and they can only hold so many unconfirmed transactions in their mempool.

Once the transaction confirms everyone will hear about it because it'll have been incorporated in a block. So I wouldn't worry about it.