It's like he's developed a habit to "need" that night time feed. Do you do a dream feed? If not, adding one might help. Otherwise, it might help if you keep a record for a couple of nights of when he wakes and how much he takes. Then, on the first night, you feed him an hour before the earliest time he woke up (ie if he woke at 4,3,4,3,3, you would feed him at 2). Feed him as much as the biggest feed he took. Each night, cut the feed by one ounce and add that ounce to his day time feeds to make up for it. So then, if he wakes up an hour or two after feeding him, you know it's not hunger and can then use PU/PD or pat/shh or whatever to get him back to sleep.
FWIW, our dd is 6.5 months old and has a 6 ounce dream feed around 10/10.30 each night. I hope to wean it in the next month or so.
