No, I don't think he was covering for Dawn, mainly because he refers to the spell later in the season, and it didn't look like Dawn recognized the amulet when she took it, because she was a total klepto.
Also, in 'Selfless' during S7, we see a flashback to Anya the night before OMWF, when the spell first kicked in. Xander's asleep on the chair when Anya starts sining, and he mumbles something about a spell, and singing and happy endings.
So, no, I don't think Dawn was responsible, I think it was Xander.
Also, in 'Selfless' during S7, we see a flashback to Anya the night before OMWF, when the spell first kicked in. Xander's asleep on the chair when Anya starts sining, and he mumbles something about a spell, and singing and happy endings.
So, no, I don't think Dawn was responsible, I think it was Xander.