A long time ago, I posted a blog on the meaning of grace.
You can read the whole thing, but essentially it comes down to a discussion of "favor that is granted outside the bounds of contractual obligation." However, this does not mean it is necessarily "unmerited" or "uninstigated." In my book I give the example of Cornelius [among others]. In the case of Paul, the point is that Christ's coming was not a blessing obtained (and hence exclusive to) the Jews based on their keeping the Mosaic regulations and ordinances (and hence Gentiles are not bound to convert to Judaism to benefit from Jesus' work.)
Someone wrote me a question regarding this topic, and in answering it I noticed a place where Christ refers to grace/favor (Greek = charis) in terms where it is clear that the grace is not without instigation: Luke 6:32-35
Indeed, if one reads the Matthew version in parallel to Lukes (c.f. Matthew 5:46- 6:4) we see Matthew using the term "reward" in the same way that Luke is using the term "favor/grace/credit"
Of course, this is not to say that favor/grace/credit always refer to an instigated boon, but does show that the principal idea of the term is not "without reason," as is often thought.