  Let $\{F_n\}$ be the sequence of the Fej\'er kernels on the unit circle
$\mathbb{T}$. The first author recently proved that if $X$ is a separable
Banach function space on $\mathbb{T}$ such that the Hardy-Littlewood maximal
operator $M$ is bounded on its associate space $X'$, then $\|f*F_n-f\|_X\to 0$
for every $f\in X$ as $n\to\infty$. This implies that the set of analytic
polynomials $\mathcal{P}_A$ is dense in the abstract Hardy space $H[X]$ built
upon a separable Banach function space $X$ such that $M$ is bounded on $X'$. In
this note we show that there exists a separable weighted $L^1$ space $X$ such
that the sequence $f*F_n$ does not always converge to $f\in X$ in the norm of
$X$. On the other hand, we prove that the set $\mathcal{P}_A$ is dense in
$H[X]$ under the assumption that $X$ is merely separable.
