My baby is 6 weeks old and for the past week has been really unsettled when we put her down at night. She falls asleep after a feed so we put her in her crib and she screws her face up, almost like she is straining, makes lots of grunting/straining noises,squirms,it just goes on for hours. It's like she is uncomfortable but doesn't seem distressed when we pick her up, but most of the time she just does it for hours without a big cry and never goes into deep sleep at night.

Should I be concerned or is it normal ?

She is exclusively breastfed.