sleep troubles

My almost 11 month old never gave me any trouble going to sleep at night. But for the past 2 weeks or so, she's been fighting bedtime. It takes upto 1.5 hours for her to fall asleep. She just tosses and turns, sits up and bounces, tries to find anything to keep herself from falling asleep even though she's tired. I make sure she doesn't take a nap so close to bedtime.Thankfully, once she is asleep, she doesn't wake up throughout the night. Maybe her teeth are bothering her. But I'm wondering if anybody else is experiencing this?