Sleep Regression?

I have a sweet, 10hr/night sleeper who also has 3-4 naps a day. She is a formula babe, eats 5oz every 3hrs. Ever since her 4 month shots on Thurs, she has been a terror-fighting naps and bedtime, waking 3x a night (we usually just have to stick her pacifier back in her mouth and she goes back to sleep). Anyone else starting to see this??