What's the best way to deal with a small gap in a vinyl floor seam? Can the hair-dryer heat trick allow the flooring to be pushed to close the gap? Is there any kind of caulk or grout that can be used to fill the gaps? Thanks for any help!

We had a sheet vinyl floor installed over concrete last fall in our partial basement....installer first put a skim coat of concrete down - let "cure" about 2 hours, then laid the floor using manufacturer's recommended adhesive. At that time he told me that I may see some "bubbles" in the floor over the next few days...that was normal (?). That never happened, but 6 months later a large area of the floor..toward the middle bubbled up!! note: we haven't had any water down there. He was here and cut that area to check for moisture....there wasn't any..rather, the floor beneath was tried and flaky!! What causes this and what are my options now for a replacement floor. I appreciate any help/info.....please!! :)