I'm just a bit confused by your post. Do you mean she used to sleep through and now needs a feed by 4am?
That, I am afraid, is totally normal. As they get bigger, many babies feed more frequently. Studies have shown weaning makes no difference, as first foods you can physically give at this age (and early weaning is 17 weeks, with 26 weeks recommended as standard) are only things like carrot or baby rice, which are much lower in calories than breastmilk or formula. Watching you eat, chewing on fingers and drooling are developmental stages, not hunger signs.
There's also a thing called the four month sleep regression. Lots of babies who have slept well until that point go backwards. And some delightful ones who are tough get worse!
I would feed her when she first wakes if it's not too early - which in my book would be from a couple of hours after her last feed. I'd try to resettle without if it was much less than that unless I'm feeling lazy or too tired. You may then find she goes much longer before the next wake.
Just for comparison, my four month old was up for a feed at 10:30, 12:50, 2:51, 4:50 and then came into bed with us and snacked until around 6am then slept until 7 (am not normally this anal about the times, just slightly freaked by the perfect regularity of the waking atm). That is totally normal. She's got probably another 2-4 months where I'll accept that pattern before I start gently trying to stretch the feeding periods at night to closer to 3 hours if she hasn't done so on her own.