Absolutely. My son jump 5-6 grade levels in reading in kindergarten. And I had no idea he was gifted before he was IDed at school. He was quite intense and questioning as a toddler/preschooler. He was verbally precocious. People would comment on him and call him an "old soul". But didn't show academic interest particularly early. He was interested in math and showed understanding of conceptual math topics. He also loved to discuss and explore duct work, plumbing, gutters, drains, etc etc etc ... I remember getting trapped outside buildings with him while running errands because he wanted to discuss how water got off the roofs of buildings.
Now, as a 9 year old, I suspect he would qualify for DYS if I had him tested (hard to justify given local cost of testing and the fact that we already pulled him to homeschool). He has achievement testing that shows him in the ball park. He about drove me bananas as a preschooler.
My daughter who just turned six is just starting to show her colors. She doesn't read much willingly, but I just assessed her at about a 4th grade reading level and I suspect that's going to leap even more once we start homeschooling this fall. She has similar intensity, but wildly different interests.
