page contains too many H1 tags

Hi there! I've noticed recently that whenever I run my website through an SEO checker online, the report comes back saying that my page contains too many H1 tags. It seems to have appeared with my last 10 blog posts, but I don't think I've made any detrimental changes to my Wordpress site in that time. How can I track down the issue to correct this? Thanks! - Darlene