But was she made Colonel - or Lieutenant Colonel?
The latter sounds much more likely, for no less than four reasons.
1) It would only be a single step of promotion, therefore not unusual.
2) It would also match the Starfleet rank of Commander that Kira carried when working for the Cardassian underground; it would make no sense to give Kira a Starfleet rank that was lower than her real Bajoran rank.
3) It would keep Kira one step below Sisko in rank, which is not only dramatically satisfying in its simplicity, but makes sense in the organizational setup of the space station.
4) Kira's rank insignia are different from those worn by Colonel Day in "The Siege". This at the very least proves that the Bajoran militia has two ranks that both are addressed as "Colonel". A closer look at the rank pins also suggests that Day's brass diverges more from the Major pin than Kira's does, thus suggesting that Kira is the Lieutenant Colonel and Day is the "full" Colonel.
Naturally, anybody holding the rank of Lieutenant Colonel would still be addressed as "Colonel" in most situations.