Dan, it's been a number of years since I read Plantinga, and I did not read that much of his works. But it seems to me that the word "experiential" may take on different meanings from the meaning of Plantinga's argument. Experience is a valid addition to epistemology; it may not be provable in each case, but it is yet undoubtedly an experience. I don't remember any of Plantinga's examples, but one example would be the parting of the Red Sea. A whole nation saw it; two in fact, but only one lived to tell about it. And all they had for proof was that they all witnessed and experienced it. It is a valid grounding for what they believed, that God is there and that He acts into creation. And there is no argument that can counter it, for it really happened, whether or not there is physical or argumentative evidence to prove it,
Granted, this is my own attempt at trying to get across what I got from Plantinga. This is as much as I got from his idea of "warrant". My reading of him is confined to the few articles that I could find on his website, and to articles that appeared in about two decades of issues of a philosophy magazine which I managed to get hold of. So I don't really know for sure whether he includes "religious experience" in a universal way. I hold to a difference in a religious experience in an open canon era to one in a closed canon era. Up to the time of the Apostles it was used as proof of God's word through man; but upon the writing of the New Testament, it has become a sign to us of coming apostacy. For men will do signs and wonders in order to deceive, as if to prove their being sent from God, but offering stange new teachings. We're not to believe a different doctrine even if it is an angel that gives it to us, as opposed to angels being used numerous times in the open canon era, when God's Word was still being added to.
Still, though, I know that my Redeemer liveth, and that trumps all the irrefutable arguments that are offered to counter that certainty. Whether that is what Plantinga meant is more than I know.