Some females do make nests, but chances are that little one is a male PK.Could you please try and take another photo with his ventrals (the two long 'arms' near his/her belly).Try this article, I think it would be really helpful - http://ausaqua.net/files/sexingbettas001.html ♥ ♥ ♥Sarah. :)
It's def. a plakat, watched him flare today and his tail is def that of a ( pk), that, and he keeps making bubble nests.
Haha well lucky you. :)PKs are great, but are super high jumpers - make sure to keep a lid on for your little guy.