Hello. Yes it is imperative that there are sufficient expansion joints. This means that every 20 feet or so the grout joint should be filled with a flexible caulking rather than grout. If this is not done, you run the risk of having some of your tiles pop up from the expansion (a condition known as "tenting"). The good news is that many grout manufacturers are making a line of sanded caulking to match their sanded floor grout so the difference should be minimal. Still, you may notice a slight difference so the key is to place the expansion joints in less visible areas such as doorways or in a spot where furniture will be placed. So help your crew decide where to place them. That is actually a sign of a knowledgeable tile crew if they are suggesting expansion joints. Just make sure they use a brand of grout that has matching grouts (TEC, Custom Products, or Mapei, along with many others have matching caulking). If you are using black or white grout, however, you can simply use a generic caulking.

Glad I could help put your mind at ease and that everything worked out to your satisfaction.