Its not a problem if you have reached your level you will win and lose and hence maintain your correct grading. I have reached my level and win and lose up and down like a see-saw.
Don't misinterpret me you may be able to improve if you take the appropriate steps, change your style, try some of the helpful suggestions on this site.
I always seem to either have a long winning streak or a long losing streak. Anyone else get this problem?