J.P.
J.,
You didn't mention whether or not you put her down at night asleep or awake. If she's going in asleep, then it is likely that she is waking up after her first sleep cycle (30-40 minutes), confused. Confused about how she ended up there and where you went since you where the last thing she saw before peacefully dozing off. That is just a developmental stage before she realizes that things that are not seen (you) are not gone forever. Hide and seek helps with this a little but mostly just growing helps. If you are up to it, try putting her in bed sleepy but not completely asleep, so she has an easier time adjusting to the whole process.
good luck