How to resolve the error "You've reached the threshold of 1000 combined image exports and chart saves per day"

Dear all, I just upgrade to the personal plan, which can generate 1000 pic/day. But I only generate about ~150 pics, and still got the following error. Is this normal? Was the day count on a natural day or 24 hours? Thanks.

plotly.exceptions.PlotlyRequestError: Hi there, you’ve reached the threshold of 1000 combined image exports and chart saves per day. If you need to raise your daily limit, consider upgrading to a Professional Plan (see: https://plot.ly/products/cloud).

I am experiencing the same issue have not run many charts today. Could plotly please advise? I also have the personal plan.