sleep walking?

Aidan is now sleeping full time in his big boy bed. We have been working on that because we need his crib for Isaiah soon....I hope.... Aidan has been doing pretty well about staying in bed now, he only gets in trouble every once in a while for getting out. If he wakes up in the mornings before its time to get up we let him get books and take them back to his bed to look at while he is waiting. He seems to like sleeping in the bed, especially because it has car sheets which we only put on that bed. Two nights ago he started crying in the middle of the night, he doesn't usually do this so I went to check on him. He was standing in the middle of his floor, looking tired and kind of freaking out. I picked him up and put him back in bed and calmed him down a bit, he pretty much kept his eyes close the whole time and went back to sleep with in a minute. It was really weird. I kind of think he got out of bed while he was still sleeping and then woke up standing up and didn't know what was going on. It was kind of funny too. He didn't do it last night, lets hope he grows out of it.