Well, if she were sleeping more like 11 hours, then I'd say she's just getting rid of night sleep b/c she's getting older and needing less sleep overall. BUT, it's actually more like 10.5 hours and you're saying she's grumpy.
To me that short nap says OT at bedtime. Even though you've been on the same routine for awhile, it could be that 2 yr molars are starting to bother her, making her more tired. Or she could be coming down with an illness, going thru a growth spurt, etc. I'd try putting her down for bed at 7:30 and see if that helps. Sounds like she's doing about 6 hours A time post-nap which is quite a lot compared to her pre-nap A time. My LO has slowly shortened his post-nap A time thru the toddler years. When he was 18 months, the two A times were exactly the same. At age 2.5, he needed pre-nap A time to be 5 and post-nap A time to be 4.5 hours. Now at 3.4 he only can do 4 hours post-nap! It's weird, and I just think it's all the stuff that goes on with them physically, mentally, emotionally at this age.
Long story short : early bedtime of 7:30 for 3 days and then if that doesn't help I'd even try a 7 pm bedtime for a few days and see what happens!
