In the case of a Houston home daycare worker, who left her charges unattended in February while she went to Target, 4 of the toddlers died in a fire started from items cooking while she was gone. Jessica Tata has 4 counts of felony murder against her and is awaiting trial next year. Part of the evidence against her is the store video of her checking out at Target during the time the fire is estimated to have started.
http://www.kens5.com/news/125518713.html
IF the store video of DB is evidence that she left the baby unattended, and IF a tragic accident happened during that time, she may indeed be fearful of the same type of charges against her. That would be a major motive to cover-up the accident.
BIG IFs, and all speculation on my part.