Baby taking less formula at night?

[minibmw2010]

My DS (nearly 10 weeks) has stopped taking his full feed of 150/200 ml at night and stops at 100 dead and goes straight back to sleep. I generally have him down by 7.30 after his bath and a full feed, he sleeps until about 10.30/11 and i feed him again which is when the 100 feeds start. Any ideas if I'm doing something wrong or if this is ok?? I thought if I want to try and stretch him between feeds he needs mire not less ??