I just upgraded my license to Extra about a week and a half ago, so perhaps I'm supposed to know this. The FCC database shows my upgrade to Extra, but the expiration date and callsign haven't changed. I thought that my license would be renewed, at the very least. Can someone shed some light on this?
Renewal, upgrade, and change of call sign are three separate things, except that renewal and change of call sign may be requested together.
§97.21 Application for a modified or renewed license grant.
(a) A person holding a valid amateur station license grant:
(2) May apply to the FCC for a modification of the operator/primary station license grant to show a higher operator class. …
(3) May apply to the FCC for renewal of the license grant for another term in accordance with §§1.913 and 1.949 of this chapter. …
As to your callsign,
(c) Except as provided in paragraph (a)(3) of this section, a call sign obtained under the sequential or vanity call sign system will be reassigned to the station upon renewal or modification of a station license.
I vaguely recall that you can ask the VEs to get you assigned a new sequential call sign when they submit the upgrade on your behalf, but I'm not sure about that.
What you can do now: you can apply for modification of your license, or if within 90 days of expiration, a combined renewal and modification, which may either:
Request that you be assigned a new sequential call sign, which will be from the series for Extra class operators, or
Request a vanity call sign chosen by you (subject to the restrictions on vanity call signs).
For details on this process, see Form 605 (PDF), which is the form for all license renewals and modifications, and Schedule D in the same document, which is abut amateur radio call signs in particular. (When you actually go to make the request, you would usually do it through the FCC ULS, not by filling out this form on paper.)
Unless your license was set to expire within the next 90 days, it won't be renewed.
From the back of NCVEC 605 or numerous times on FCC 605:
License renewals (with associated fee for vanity renewals) may only be completed during the final 90 days prior to license expiration, or up to two years after expiration.
As for your callsign, if the box labeled "CHANGE my station call sign systematically" was left blank, your callsign would remain the same.