Any change in her wake up time? I find with MArgot that she sleeps a total of about 11.5-12 hours a day (she's 30 minths)divided between naps and night sleep with anywhere from 0 nap to 12 hours of sleep or a 2 hour nap and 9.5 hour night sleep, so I think there can be a lot of variability from day to day in when lo's sleep.
the reason I asked about the wakeup time is that I find when Margot sleeps closer to 7 o'clock ( her usual wakeup was closer to 6:30)which happens a lot lately she either will not nap or will not nap until later ie. 1:30 instead of her usual 1 o'clock, so your lo may not be tired around the time she normally naps and then she "gets passed it"