While the explanation in the FAQ leaves little room for doubt:
"No—the spell must be played as part of the current check for Blessing of Pharasma to add 2 dice."
The resolution leaves room for abuse in my opinion:
On the blessing Blessing of Pharasma, in the second power, replace "to add 2 dice to a check when playing a spell" with "to add 2 dice to a check if a spell was played during that check." (Note: This card also appears in the Character Add-On Deck.)
So character A encounters a monster that threatens to stomp him into oblivion and his draw pile is woefully short. Character B at his location decides to toss a cure his way to bolster up his deck. (The timing on this has always seemed a little odd to me but I've found nothing to indicate it isn't legal). Character A then plays a Blessing of Pharasma to add 2 dice to the check since a spell was played during the check. Obviously this isn't the intent as the explanation specifies that a spell must be played as a part of the current check and this certainly wouldn't apply but using the suggested wording it could certainly be argued could it not?