No problem, Peter, I do it on that chord formation too. It only becomes a problem if you have to rely on the support of the second finger to get a clean bar chord. That's why I give my students a six-string F major as their first full bar chord. But before that, I have them sneak up on bar chords with partial bars, like A7, for example.

If a person can do a full six-string bar with just the index finger, then there's no problem using the second finger for extra support when you don't need it elsewhere.

Don Firth