There are several things it could be.

1. They want more cuddles
2. They're trying to increase your supply (not an under supply)
3. They're having a growth spurt
4. They are not feeling well or too cold etc
5. They are going through a new developmental milestone ie, rolling, crawling etc.

Don't blame yourself or your supply. Babies just like to test us lol, its all a learning curve.

Sent from HTC wildfire using TAPATALK, so forgive any spelling errors its a small keyboard.