Thanks girls.

kazbah - I guess it could be the teat, tho he's been on the same style of teat since day dot and hasn't had a problem until now. If it persists I might have to look at changing (I hope not tho...just bought a whole heap of new bottles & teats!! )

Storm - great to hear you went through something similar (well, not that I'm happy you did, but nice to know I"m not alone!). He generally has 240ml per feed, 4 times a day. Tho I am beginning to wonder if perhaps now he doesn't need so much, he has left 30-odd mls a couple of times. Fingers crossed its just a phase!