WIthout being able to see it, it may be hard for someone here to determine if it is an actual cut. If your baby is not fussy when you touch it, then it probably could be nothing more than a slight nick with the clippers. In another thread where groomers were being discussed, several people stated that their babies move around while being groomed. You have to remember, they aren't always going to stand perfectly still when being groomed, even at home, so accidents are going to happen. If this is a cut/nick from the groomers, what I'd be most upset over is in their not telling me (provided they were aware it even happened). Don't "close the book" on this groomer just yet if you were satisfied with the work provided. Just keep an eye on your baby's paw and as long as there is no limping and you are allowed to touch it and look at it without upset, I wouldn't worry about it
And I understand what you mean about finding a good groomer - took me a while but I found one here and she's wonderful!
Have a great day