Haley - separation anxiety? sudden change of act...

Haley has such a strong will.  Her stubbornness is driving me nuts.  Lately, Haley becomes very attached to me.  Separation anxiety all of a sudden becomes an issue.  No matter where we go...school, dancing, awana, church nursery, she sometimes will not let me go or she will start to cry.  Haley wasn't like that before.  She didn't even cry on the first day of school.  I had to leave as soon as she walks into her class so she won't have time to drag on asking me to stay.  On Awana awards night, she demanded mommy to go up to the stage with her.  I prepared a bucket of treats with all her favorite snack as a price if she went up there by herself.  It didn't work.  At swimming class, she screamed and cried when the male substitute teacher approached her.  She refused to go into her dance class this past week.  After I bribe her with treats, she went in by herself.  I walked into the classroom toward the end to record the dance so we can practice at home for the upcoming recital.  She stopped to dance and started to cry as soon as she saw me.  In the combination of different incidents, I think I have to be firm and begin to train Haley back to independence.  I need her to learn to be independent when either mommy is present or not.