The suggested edit notification has been consistently wrong (in an inconsistent way) for a few weeks now. No amount of refreshing and cache-deletion seems to fix it.

It's always off, but the amount by which it's wrong varies.

Is it just me?

This stopped happening for a while, then started again..

It won't, at least not always. The review indicator in the top-bar is not calculated on a per-user basis, but on a per-site basis. The counts in the review queue itself are calculated on a per-user basis. The top-bar indicator also won't always be accurate (and it's cached), which is why the tooltip has a ~ to indicate it's an approximate value.