16 month old waking in the middle of the night, and won't go back to sleep. Advice???

So our daughter has been falling asleep on her own since 4 months and sleeping through the night since 8 months. She has always been a GREAT sleeper. But for the past couple of weeks, she wakes between 1-3 AM and won't go back to sleep unless my husband or I goes in her room and lays down beside her crib. When we do that, she will immediately lay back down and go back to sleep. We're at a loss of what to do. We don't mind going in and comforting her if she's just going through a phase and needs some extra comforting. But we don't want to create bad sleep habits.

Has anyone else gone through this? How long did it last and how did you survive? 😅