Hi!
I have a yorkie named Bailey with tall legs.
I got him from a very good breeder (she shows her yorkies at dog shows and is really concerned with the proper looks and behaviour)
Bailey's mom was a show dog champion and she is a tall legged yorkie (weights 4 lb). His dad on the other hand is short legged and is 3.8 lb.
There were two male puppies in this litter. When I was talking to Bailey's breeder on the phone she asked me whether I wanted a short legged puppy that took after his mom or the long legged one who had shorter legs like dad. I had no idea!
When I visited, I couldn't really see much distinction in the structure of their legs myself, but one puppy was bigger than the other in general.
I picked the bigger puppy (they both were still super tiny)
Mainly, I picked Bailey because of his personality, but also I thought that he may be healthier than his super tiny brother. I met both of Baileys parents and they were both very cute looking.
I only saw the difference in legs, when the breeder placed his parents side by side to show me what she meant. But, unless you look at them side by side It's difficult to tell the difference. If anything, I think the fact that you are being told that this puppy is long legged means that this breeder knows what she's talking about.
Bailey has grown to be bigger than his mom and his dad. He is about 6 lb, last time I checked. He feels pretty light and skinny though.
His legs are on the longer side, but it allows him to be able to jump on and off the couch with little effort. He can also run up and down the stairs very easily. It's also funny how he can hide his legs and roll in a very small ball when he sleeps, or be able to wrap his long paws around your neck when you carry him around.
I wouldn't worry too much about the long legs, because unless you put two yorkies side by side, it would be hard to tell the difference.
And besides it is a totally normal for a purebred yorkie to have longer legs (Bailey's mom who was a show champion has long legs)
Hope that helps! Please post some pics when you get your little one!
I'm sure he'll be super sweet...
Oh, and here are some pictures of Bailey. He's currently 9 months.