Yes, that’s right, Calvin said “offer” (not demand) as in “free” or “well-meant” offer of the gospel.
Update 7 Jan 09:
For more on this question see ” Janus, the Well-Meant Offer of the Gospel, and Westminster Theology,” in David VanDrunen, ed. The Pattern of Sound Doctrine. See also James Durham Thesis which has a running series of posts on the history of the Free or Well-Meant Offer of the gospel.