If you are getting invalid SSL certificate error in the browser when serving assets from the s3 bucket and using s3 bucket name as a subdomain. This quick tip might be a help.
In my case, I had a dot in the bucket name so the domain created was like https://akhil.bansal.s3.amazo…… I removed the dot from the bucket name and it worked perfectly. Looks like S3 ssl certificate does not support a dot in the subdomain.