Why does GTM use probers not in the prober pool?

I think I have found an answer to my own question, so I will post it here for others and for comments. I found this in the prober pool documentation “If all of the members of a Prober pool are marked down, or if a server has no Prober pool assigned, BIG-IP GTM reverts to a default intelligent probing algorithm to gather data about the resources on the server.”. When I went back through our logs I noticed that around the same time this event occurred we also had logs showing connectivity was lost to the probers in the pool, so it looks like when that happened the GTM delegated to available bigip devices that were not part of the prober pool.