I would say feed of the cue's your daughter is giving you. If she appears to be less happy, not wanting to go i'd look into it further. Also talk to your provider and find out what types of activities she is doing with your daughter to hep her learn at an age appropriate rate. perhaps your provider does playdates and outings with other 3 yr olds and maybe she is looking into taking another child in her care that is closer to your daughters age.
i am sure your daughter is taking on a big sister role with the little ones and she probably quite enjoys helping out and entertaining them. it is a great way for her to gain leadership skills, patience, understanding and being a role model.