I agree with Forward Handle. A well made wooden bow by a good bowyer will be adequately 'shot in' before he let's it go. It should not, would not, take noticeable, additional set in the first week, or first few hundred shots by the new owner, unless it has soaked up moisture, been drawn considerably differently, or been drawn farther than what it was built and trained for... assuming it was properly built and trained. It should already have been drawn hundreds of times in increments during tillering, and then after it reaches full draw and been exercised there many times, should have been shot in 150-200 times, at least, during which any tiller changes and/or set is assessed and addressed... any set should be water under the bridge before it left his possession. Something along this line is the proper, responsible way to treat a bow, and receiver of it.
However, it COULD be that it was designed and constructed well enough, but was rushed a bit and he just didn't take the time to shoot it in properly. Not good, imo, and it would lead me to wonder what other shortcuts may have been taken, but my point is, that little bit of set may not necessarily mean it's going to get a lot worse or that it's going to fail.
Straight wooden bows, after being strung and shot for a period of time, and then unstrung, tend to follow the string, but then will spring back toward their previous shape. They may move back over a period of several hours. So don't be too quick to judge. Don't stand it on its bottom limb in the meantime. Lay it some place flat, on a table, shelf, or something with its limbs free to relax and move back.... if you want be critical and take such measurements.
A hickory/osage/ipe trilam shouldn't take much set ultimately, unless it's underbuilt for what you're doing with it. 75# @27" aye? How wide and long is it? How far are YOU drawing it?