My answer, of course, comes from my own experiences.
I have two sons in school, one who just started kindergarten, like yours. The other one is now in third grade. He did fine in kindergarten, actually, but first grade was the tough one. He kept getting into trouble for poking his classmates, writing on their papers, etc. If he weren't so obviously gifted, we would have wondered what was going on. But I knew he was just plain bored. He skipped first grade last year. That helped his behavior, but I noticed that he's been quite grumpy when he comes home.
My second son is smart, but not so obviously as his big brother. He may actually be smarter, but it's just part of his personality that he doesn't show it. And he stresses! Oh how he stresses. But again, he doesn't show it.
It sounds like your little guy is stressed out. And if you have any suspicion of his being gifted, that could explain a lot of his other behaviors, like feeling different and not wanting to be stared at. Unfortunately, there isn't too much you can do about giftedness in kindergarten (at least in my experience) but do enrichment activities at home (basically send them to school, but keep home schooling them, too.)
It seems to me that, after a school day of stress, he is able to relax completely at home, which is why you see him so happy and smiling now. It's hard to explain what I'm thinking, something about how he was probably mildly stressed all the time before school started, but now, he gets all his stressing done at school, so he can finally relax.
I think it's too early to consider pulling him out of school. Give him some time to adjust to his new life. I don't know when your school started, but we're just in our third week! I would be willing to bet that he settles in after a few months. That reminds me--we had no idea my oldest son was stressed out until his second progress report said that he seemed much happier and open to sharing with his class now.
Updated
My answer, of course, comes from my own experiences.
I have two sons in school, one who just started kindergarten, like yours. The other one is now in third grade. He did fine in kindergarten, actually, but first grade was the tough one. He kept getting into trouble for poking his classmates, writing on their papers, etc. If he weren't so obviously gifted, we would have wondered what was going on. But I knew he was just plain bored. He skipped first grade last year. That helped his behavior, but I noticed that he's been quite grumpy when he comes home.
My second son is smart, but not so obviously as his big brother. He may actually be smarter, but it's just part of his personality that he doesn't show it. And he stresses! Oh how he stresses. But again, he doesn't show it.
It sounds like your little guy is stressed out. And if you have any suspicion of his being gifted, that could explain a lot of his other behaviors, like feeling different and not wanting to be stared at. Unfortunately, there isn't too much you can do about giftedness in kindergarten (at least in my experience) but do enrichment activities at home (basically send them to school, but keep home schooling them, too.)
It seems to me that, after a school day of stress, he is able to relax completely at home, which is why you see him so happy and smiling now. It's hard to explain what I'm thinking, something about how he was probably mildly stressed all the time before school started, but now, he gets all his stressing done at school, so he can finally relax.
I think it's too early to consider pulling him out of school. Give him some time to adjust to his new life. I don't know when your school started, but we're just in our third week! I would be willing to bet that he settles in after a few months. That reminds me--we had no idea my oldest son was stressed out until his second progress report said that he seemed much happier and open to sharing with his class now.