Babies sleep habits

Tracey
My baby is 4 weeks and 3 days. The past week she has been sleeping for longer stretches at night (typically 5 or 6 hours on a row). Last night she slept from 10-630 and I pretty much just woke her up at 630 to feed and diaper change and then she went right back to sleep and it's almost 9am and I am going to go wake her up.... 
Is this okay??? I didn't think she'd have this long of sleep so early on!