Q
My daughter will be 7-years-old in July. She still sucks her index finger at bedtime. Should I be concerned?
A
The best resource for this answer is a pediatric dentist/orthodontist. She will be able to take a look at your daughter's mouth, listen to the nature and frequency of this habit (perhaps even encourage your daughter to show her exactly how she sucks her finger) and evaluate whether this constitutes a present/future problem for her development (unnatural teeth spacing, overbite, etc.).
Other than the possible medical/dental problems this habit may cause, there is no other reason to worry about this habit. It's clearly a self-soothing, calming ritual behavior associated with her falling asleep. Get her that dental evaluation and then act accordingly. If she's told she absolutely should not continue this habit, write me some advice on helping her kick the habit.