He must have reeeaaached to grab the basket which was off to the side and pulled it onto the blanket and played in it for the remaining time of his blanket time. Until he fell to the side and couldn't get out without getting off the blanket. So he just awkwardly sat in it until he heard the timer "ding".
Blanket time is a good thing. I am looking forward to extending the time - I think Noah will do really well with it (I could have extended it today, but decided to keep with the 15 minutes for the rest of the week).