Yes, it does sound like you mounted the bindings yourself.

bindings are mounted relatively to the ski's center of balance, which
happen to coincide on two skis if the skis are from the same pair. I've
never seen more than ~5 mm difference. On pair of my racing skis has
about that much of the difference in binding position. And, yes, I
mounted them myself, and I'll never do that again (not that I notice
the difference while skiing, but it's just that mounting bindings is
not worth my time)

Speaking of left-right... I've seen, like, 2 mm deviations from the
center. Again, no noticeable effect.