First time using an engine -- shouldn't 19...Kg8 be marked a blunder?

I'm still trying to make sense of the output of the engine. I'm using Scid Vs. PC and its annotation feature. The annotation settings I used are:

Seconds per move:  [30]
Blunder threshold: [1.0]

Add scores:
    [ ] All moves
    [ ] Blunders/not best
    [o] Variations
    [ ] No

Add variations:
    [ ] When move is not the best
    [o] When move is a blunder
    [ ] All moves
    [ ] No

Which side:
    [o] Moves by both sides
    [ ] White moves only
    [ ] Black moves only

[ ] Process sub-variations
[ ] Add annotator to comment
[✓] Add annotator tag
[ ] Use book: [elo2400.bin]
[✓] Mark tactical exercises

I used both Stockfish 2.3.1 and the built-in engine Toga, and neither of them marked 19...Kg8 as a blunder/inaccuracy/etc. Why not?

[pgn] [Event "Live Chess"] [Site "Chess.com"] [Date "2012.12.01"] [Round "?"] [White "me"] [Black "WILLIE8278"] [Result "1-0"] [WhiteElo "989"] [BlackElo "967"] [TimeControl "15|10"] [Termination "ishidableach won by checkmate"] [Annotator "Stockfish 2.3.1 JA 64bit , Toga II 1.3 Beta1"]

1.e4 b6 2.d4 Bb7 3.Nc3 g6 4.Nf3 Bg7 5.Bf4 d6 6.Bc4 e6 7.O-O d5 8.exd5 $201 Bxd5 $6 $18 $201 {+3.03 / +1.61} ( 8...exd5 9.Bb5+ c6 10.Qe2+ Ne7 11.Bd3 c5 12.dxc5 O-O 13.cxb6 axb6 14.Be5 Nbc6 15.Bxg7 Kxg7 16.Qe3 $16 ) 9.Nxd5 $6 $16 {+1.97 / +3.03} ( 9.Bxd5 exd5 10.Nb5 Na6 11.c4 Bh6 12.Bxh6 Nxh6 13.Qa4 c6 14.Nc3 Nb8 15.cxd5 Qf6 16.Rfe1+ Kf8 $18 ) 9...exd5 10.Qe2+ Ne7 $201 11.Bxd5 $2 {-0.60 / +1.88} ( 11.Bb5+ c6 12.Bd3 O-O 13.Bg5 f6 14.Qe6+ Rf7 15.Bf4 Qd7 16.Rfe1 Qxe6 17.Rxe6 Nd7 18.Rae1 $16 ) 11...Qxd5 12.Rfe1 $201 O-O $6 $14 {+0.77 / -0.49} ( 12...Bf6 13.c4 Qf5 14.Bh6 g5 15.Bg7 Rg8 16.Bxf6 Qxf6 17.Ne5 Nd7 18. Nc6 $10 ) 13.Qxe7 Na6 14.Rad1 Qf5 $201 15.Bxc7 $2 $10 $201 {****D5 1.4->-0.5 -0.47 / +1.40} ( 15.Qa3 Qxf4 16.Qxa6 Bf6 17.c3 Rfd8 18.Qb7 Qd6 19.Rd3 a5 20.Rde3 Rdb8 21.Qe4 $14 ) 15...Rae8 $4 $18 {+3.92 / -0.47} ( 15...Bf6 16.Qd6 Rfc8 17.Qf4 Rxc7 18.Qxf5 gxf5 19.c3 Rd8 20.Rd2 Rc4 21.Ne5 Bxe5 22.Rxe5 Nc5 23.Rxf5 $10 ) 16.Qxe8 $201 Rxe8 $2 $18 {+5.74 / +3.97} ( 16...Nxc7 17.Qa4 a5 18.Qc6 Ne6 19.h3 Nf4 20.Qe4 Qf6 21.Rd2 Qd6 22. Ng5 $18 ) 17.Rxe8+ Bf8 18.Bd6 Kg7 19.Bxf8+ Kg8 20.Bh6# 1-0 [/pgn]