Ngolo gamble...is it deliberate manipulation of the market?

This is the third time I have seen this happen recently. So at around the same time on each occasion 6.45am an outsider is backed, in this case Ngolo which was at that time 80-1. By 7.30am the horse is 6s in places and £15 was matched on the exchange @ 7.4. Then just after 8am the horse starts to drift out again and is now back to 90 on the exchange. Is someone placing small bets knowing that because its such a big price this will set the algorithms off reducing the price disproportionately and that they can lay the horse on the exchange in the knowledge it will drift substantially later? The horse dose not need to win as if you have laid it at say 10s and you can back it back now at 90 you and make a few bob either way. Thoughts please?