Lemon Tetras Acting Strange

[Gnatfish]

Hello

I have a 15 gallon tank and my Lemon Tetras are acting strange, they've started chasing each other for fast short burst then swimming away. Its not just one doing it, its a few. And sometimes they even go after the Harlquins. Is this the males trying to impress them or something?

The tank is stocked with:

6 Lemon Tetras
6 Harlquins
2 Cories

Thanks

Gnatfish