Perfectly normal!! I'm still pretty fresh myself with only just over 450hrs, but i've decided that theres nothing wrong with some butterflies, infact its beneficial, and others with far more experience agree with me. Its those butterflies that will stop you getting complacent and/or sloppy and making silly mistakes.
The real trick is not to let those nerves overcome you, but let them work to your advantage by using them to keep you on your toes and vigilant for problems that may occur!