I saw the same thing last night on my DTC-100, without rescanning (the DTC-100 apparently handles changing subchannels within a known channel with no need to rescan, as I have seen in earlier examples of subchannel changes on KCTS).
The PSIP data labels 13-2 as KTWB-SD. It looks like they might broadcast both KCPQ and KTWB digitally on both 18 and 25. I already receive both stations on 25-2 and 25-3. I don't know where the channel 25 transmitter is located, but I get less signal "strength" (i.e., lower antenna signal reading on my RCA DTC-100) on 25 (in the 50's) than any other digital channel (they read in the 70's).
Art, do you get channel 25 up there? If not, you will likely get channel 22 KTWB content on channel 18-2 soon, so you might not need channel 25 at all.
I wonder if keeping both channels transmitting KCPQ and KTWB is a long term plan for Tribune?