Many babies can bring back or 'posset' a small amount of milk, quite often with wind during or just after a feed - it’s a common symptom and thought to be due to the developing digestive system. Every baby is different; some bring up more milk than others. It’s quite normal and usually it’s not enough to affect their nutritional intake. If they bring up a large amount, they may want to feed more often.
A small amount of liquid looks like a lot when it spills (drip 2 or 3 teaspoons of milk onto the kitchen table and see how it looks) but there's really no need to worry if your baby is growing well and thriving.