Subscribe language style problem

If users attempt to subscribe more than once they receive this message:

You have already subscribed to this site, please check your inbox.

This is a comma splice (https://en.wikipedia.org/wiki/Comma_splice)

I suggest replacing the comma after the word site with a period.

Thanks,
The Comma Splice and Apostrophe Police.
(Jetpack 3.1.1)

https://www.ads-software.com/plugins/jetpack/