Is it ok to get independent feedback before handing in thesis? I have a thesis to hand in at my university. 

Am I allowed to ask a grad student who is an expert in my field to have a look at my thesis and give me feedback (more than merely grammatical / stylistic feedback that is) before handing it in at my university?

Some personal background to this:

I was asking my lecturer once if he knows anyone who is good at subject X. He referred me to Daniel. Daniel wanted me to pay him for his service, and I was ready to do that. 
However, he then asked me whether I intended to hand in the paper, because if so, he could not give me proper advice / would have to withhold certain criticisms from me. I told him the truth and did not end up doing it. 

But is this so? Was I unknowingly trying to 'cheat'? Would it not have been good conduct, because I would have paid him? Does this make it somehow different from "just asking a friend"?
One of the objectives of gathering professors, postgraduates, graduate students and undergraduates at an university is precisely to encourage working together and cross-checking. Nothing wrong here.

If another graduate student in interested in your work, good for you! Perhaps the basis for future collaborations. If she helps you out by helping proofread your thesis, she is certainly entitled to an acknowledgement of the help in your final writeup. And you should also lend a hand, either to her or some following students, in gratitude.