being sink in his sleep

3 times this week when I have checked on Jason on my way to bed he has been fast asleep but there is sick on his bed or pjs. Its food sick rather than milk sick (eww I know, gross, sorry). I haven't heard anything on the monitor that has sounded like him being sick, just a couple of coughs. I've had to get him up and changed and change the sheets and then it takes forever to get him back to sleep. It just really worries me that he might choke on his vomit ib his sleep. He has dinner a couple of hours before bed and a bottle at bedtime. Anyone else's baby do that or know what could be causing it? He has had a cough for a while but its actually been much better this week.