Does Harper believe Grewal?

In the CBC story (here) reporting that the Conservatives have no more tapes to release, is an odd statement:

"[Harper] says he's convinced Grewal has handed over all of the recordings and believes his MP's version of events."

Actually, I suspect that Harper has his doubts. If he believed him he'd say "Grewal has handed them all over". Saying that he's convinced that Grewal had handed them over betrays caution. Being convinced means that he is willing to admit that he can be unconvinced.

[Update: Harper's exact words are quoted here:

"I have to believe what Gurmant tells me," Harper told reporters in Ottawa after caucus.

This is even more tepid than I had original thought. "I have to believe " adds another hint of mental reservation.

(As reported earlier, another Tory MP from BC was much less circumspect: here)