I've been questioning this lately too, though our issue is that she's sleeping later (wakes in the 9am hour!) and it's getting hard to fit in 2 naps. Anyways sleeping issues can also be caused by a growth spurt (prob why my LO is sleeping so late lately), teething, and learning new skills.
Do you think any of those might be the issue? I'm never sure if my LO is ready to drop the 2nd nap or if it's ME who's ready, haha.
One thing I've read about dropping the nap though, is you start at an early time like noon, and slowly push it back to the time you want your LO to nap like maybe 2pm, or whatever works for you guys.
Hope that helps!