vaguely familiar

She was vaguely familiar, he must've seen her here before.

The voice on the other end of the line was vaguely familiar.

The face was vaguely familiar, but she could not place it.

He was vaguely familiar, but none of us could place him right off.

The face was vaguely familiar, but he couldn't place it.

In truth, it was vaguely familiar, but she couldn't remember why or how.

If the man looks vaguely familiar, that's because he is.

The voice was vaguely familiar, but I couldn't make out the features.

What you're telling me is vaguely familiar. I must have read about it at some point.

Your face is vaguely familiar, but I can't remember where we met.