No no don't worry it's reasonable for you to find him creepy or uncomfortable to be around. At first you don't exactly notice one's behaviour but the more you see them, the merrier you become socially conscious. I don't think it's a bad thing that you find him now creepy, it's a good thing because, you trust your intuition. If your intuition says they seem off, you have better listen to it and try to distant yourself from that said teacher. Most of the time, your intuition may be correct about that teacher.