I would highly recommend that you ask the individual bowyer how they measure their bows, as there are some differences.
I measured my draw length with three different methods, and came out with three slightly different numbers, with the average being approx 27". I don't have my little sheet of paper with me right now, but I think I measured at 27 1/2" one way, 26 1/2" another way, and 26 3/4" the last way. I've drawn several 50# at 28" bows, and generally I pull them to 47#'s. My latest bow is marked 52# at 28". However, I measure it with my bowscale at 50# at 28" and I pull it to approx 47-48#'s (It's right between the lines). So... either that bowyer didn't mark his bow properly, or (more likely), he measures his bow differently than the ones I've previously drawn.
So that is why I say - call the bowyer.
All the best,
Glenn