I get that too. I think its because for some people stuttering is linked to their anxiety levels. Have you been stressed out lately? One good technique is to work with the stutter rather than against it. I know it sounds abstract but it works. Don't be afraid of blocks. When you encounter a block, accept it and gently try to ease the word in. You can do that by altering the pronunciation of the word or even adding in an extra vowel sound before the word.