Question: I have got a new job that needs a lot of training in the beginning. So our project manager always assigns someone to mentor the new employees.

My colleague, who is supposed to mentor me, started teaching me the aspects in the first two weeks, but after that he started acting rudely knowing that in the real world he is still friendly. 

I am not a pushy person and I always ask politely and thank him every time he helps me. However, he acts like he didn't hear me when I call his name, he acts like his eyes hurt and he can't read anything on the screen, he acts like he is very busy doing something and he even once told me that he is not paid for doing this.

The strange thing is that he helps other people doing their work after acting with me this way.

I don't know why he does this with me and how to solve this issue? Should I tell the project manager about this or not?

Answer: 
This sounds like you disrespected the time of the mentor and asked the same questions repeatedly or asked things that you should have been able to easily look up yourself. Usually when people start out friendly and then act this way it is because talking to you has become a burden keeping them from doing their own job. 

You need to research as much as you can first and show him how you have tried to solve the problem. When he tells you something, you need to take actual notes and before you go to him again, review those notes and see if it is something he told you before. You might want to talk to him only once or twice a day and save up several questions. You might also want to talk to him directly about the issue saying that you noticed that you seem to be annoying him and how would he prefer to work with you to get you up-to-speed. Then follow whatever suggestions he makes.
The very best thing to do is ask him for a few minutes of his time, at his convenience, and ask him outright. This need not, and should not be confrontational, but ask if he is still interested in mentoring you, and if he is resistant, what could be done about it. If he's just having a hard time, and has a lot of pressure, he might be acting this way because he is struggling himself. If this is the case, you can one or both approach your project manager and discuss a re-shuffle of his responsibilities with respect to mentoring you. Please be careful to make sure this conversation doesn't sound like you are accusing him of anything, particularly of being incapable, as he will probably take exception to this and become more difficult to work with.

On the other hand, you may very well have done something to warrant his reaction, if so, the initial conversation can also shed some light on this. In my experience, some folk have trouble admitting that they are annoyed with somebody else for a plethora of reasons - so break the ice yourself - ask if he is displeased with your response to his mentoring, and discuss any weaknesses you may have with him. Try to schedule some time to really crack any difficult topics you may have asked him about a few times, but might have been too embarrassed to admit to not grasping. Also try to come up with a more structured approach to any mentoring - maybe a brief 2 minute summary each day/week to air out any problems in smaller chunks.

If there is not a reasonable outcome, you may then want to discuss the issue with the project manager/senior person to control the situation with more structure.

Be open to the extremes of possibility: that you may have annoyed him, that you might not be the reason for his reactions, or that he just plain doesn't like working with you.

Good luck, and I hope you resolve this.