This: I'd say something is definitely off.
In addition to the above, I'll simply ask if your other 3 needles are accurate? For example, when I took my cluster apart to swap to US gauge faces, I didn't get all 4 needles back on perfectly. My speedo is ~3mph off, and my temperature gauge sits at 12:30, instead of 12:00. It annoys the eff out of me, but taking that thing out/apart again isn't something I'm dying to do.