Originally Posted by CliffordK

The seat tube angle will also change (reposition seat rails?) And the bottom bracket will drop about half that amount, or about 2mm.

I assume you're measuring to the top of the crown (crown race) right?

Do you have a sloping top tube? If not, it may start sloping, but you probably won't notice it.

Anyway, I believe there is a lot of tolerance in the bikes, and you may initially feel a slight difference in the bike, but you'll habituate to it quickly.