Piano mid-range sounds like strings

A few months ago, I was at a concert with my local orchestra and they were playing a piano concerto (I don't remember what concerto it was). At some point during the piece, while the pianist was playing solo around the middle range I actually though I heard the violin section playing, but they weren't (it wasn't just similar, I genuinely though I was hearing strings for a split second, and only noticed I wasn't when I looked). A few days ago I was playing the piano myself at home and the same phenomena occured. Those were the only times this happened to me, and strangely I'm not able to force it, it just happens. Has anyone else experienced this?

I haven't, no.

But they're both string instruments and I guess they do have a somewhat similar, resonant timbre after the initial attack

Makes sense