You can take a mister and spray a mist over the eggs. If you humidity is too low they may get stuck. It won't hurt to mist them. Many breeders I know do this too. The humidity should be between 65 and 70%. You can also use a Q-tip dipped in water and swab where the chick is stuck to the shell.
Not to worry. If your temp is 99 they can arrive a few hrs later. The lower the temp the longer it takes for them to hatch. The higher the quicker they will hatch. I keep my LG at 100. It went up to 101 and I had some chicks hatch on day 19. I had just taken the egg turner out the night before...