Doe's my piggie like me?

Hi, can anyone help with my piggie?
I have just bought a pig a few months a go,and every thing has been great, he's a very healthy pig and he is well cared for and i love him very much. But the problem is is that he wont stop making a rumbling sound when i go near him to try to stoke him or just when i stand by his cage to talk to him for comfort, as i think hes scared, but when i do stroke him very gently and calmly, he begins to rumble,move his hips from side to side, and then it results into an aggressive bite, not hard enough to break the skin ,but it still upsets me, as i think he doest want to be with me or know me. Can someone help me and tell me what this means,does he hate me or am i just over reacting?.