Should a Blog Post Title be H1 ?

Is there any problem with using H1 tags in blog post titles? I mean, there are many posts on one page, and then many H1 tags on each page.

 

I am using wordpress, what I do is to modify the code such that the title of a post will be in H1 when individual post is shown. While on other pages (index or category main page), I will keep the titles in h2.

 

Hm, so do you ever use H2 on subtitles?

 

I don't think there are any problem you can use on every post