Siggav makes a good point. Maybe you were on an uphill climb for a while with all the excitement that comes with learning, and now you've slowed down a little bit but have the same expectations. I'm going through that with running, in a way. I keep getting faster and going further, and it's awesome, and then I'll have a bad day. My coach keeps reminding me I can't set a PR every time I run. There will be ups and downs, so set your expectations accordingly. Just go out and enjoy your dance.