Grad Students - How typical is it for your supervisor to re-write your proposal?

I mean edit it so heavily to the point it's re-worded/structured completely differently to what I wrote (although the ideas are pretty much the same). I don't know whether to feel grateful or upset!

Has anyone experienced this before?

Seems a bit excessive - what were his/her reasons for doing it? It's one thing to nudge your proposal in a certain direction, or help you to clarify your ideas, but rewriting it is odd. You need to find out what was wrong with it in the first place...

I think he is a perfectionist ! The thing I'm worried about is that this will become a continual pattern and I will forced to adapt the tone and style of my writing to the extent that I become him!

It's important to stamp authority onto your own work at the beginning of a supervisory relationship - you don't want to end up having written someone else's thesis. If he's rewritten your words but kept the ideas intact, that would suggest he thinks there's something wrong with your expression. Perhaps you should talk to him about this. Any writing problems need to be smoothed out early, otherwise writing a thesis will be even more difficult than it usually is; and they won't be smoothed out by him rewriting things!

Look at your original version and then at his. What are the differences? Do you feel he has improved it? If so, why? Definitely talk to him about it. He must have given you some idea of why he chose to rewrite it.

I think he is a perfectionist ! The thing I'm worried about is that this will become a continual pattern and I will forced to adapt the tone and style of my writing to the extent that I become him!