Baby slept through without waking, is this Ok or risky?

[Katekoom]

Hi,
My 3 week old usually wakes every 2-4 hours to feed at night. Sometimes I have to wake her. She's a big baby and has (after an initial wobble) been putting on regular weight, she's now about 9lb.
Yesterday she didn't sleep much in the day and had a fussy cluster feeding evening, I could tell she was really overtired. Then last night she slept 5.5 hours.
I've read that a baby can dehydrate if not woken at night, but does that just apply to very new babies?
I don't know wether to celebrate the sleep or feel guilty for not waking her when my alarm went off (my husband suggestion which at 3:30pm seemed like a seriously good ideidea!)
Help! I'm worried I've damaged her

3:30am sorry

I've heard it said that cluster feeding is related to learning night and day / stocking up to sleep longer in the night. It's never worked that way for me but sounds like it might for you!

I wouldn't worry about dehydration unless your baby is ill - if she was thirsty I'm sure she would have woken. Check her nappy is wet - if she is weeing and seems well she is not dehydrated.

Equally I wouldn't get too excited either, just enjoy the fact you got a good stretch of sleep. It might not happen again for a while.

My DD slept full 9-10 hour nights from about 6 weeks. I was in the GPs about issues with DDs chest and weight gain and told her it freaked me out, as I had been relying on her to wake me (knackered), but she said I shouldn't worry; some babies did that and 'I was one of the lucky ones'. Indeed, nothing changed after she recovered and started feeding better.

Too may 'she's.... I hope you realise the 'she' that referred to the GP and that which referred to my DD