Yes absolutely normal. Even adults will do that sometimes. Chickens are basically cowards. They can be scared of anything strange or different. I can carry a feed or water bucket around them without a problem but if I’m carrying something different like a tiny camera they can freak out.
I feed mine a lot of different things from the garden. Sometimes I’ll toss something in the run that is recognized as a great treat, like cabbage, and they are really reluctant to approach it. They usually do eventually but it may take overnight for them to build up the nerve to try it. Once one builds up the courage to try it though, the rest usually swarm in.
One time I gathered a small yogurt cup full of corn ear worms when processing some corn from the garden. I dumped those out on bare ground around some 10 week olds that had been free ranging for a few weeks. At first, the chicks just looked at them, then a few started to creep stealthily toward those worms. A worm moved! Run away! Run away! They gathered themselves and gradually started approaching again, very cautiously. A worm moved! Run away! Run away! This went on for several repetitions, but eventually one of the chicks managed to grab a worm. They were wiped out in a mad feeding frenzy in just a few seconds.
So just be patient. One will eventually try it and like it. Then they will all be eating the lettuce.
