Went on a flight today in preparation for a checkride tomorrow. Noticed the standby attitude indicator (G1000 C172) took about 10 minutes or so to finally level. I started, did the run up, verified level on the ground, was departing the pattern and noticed it was cocked to the left in a 30* bank (my guess is after the initial turnout). After another 5 minutes or so it slowly came to level, then I sort of forgot about it. So going through 91.213: i) Not part of the VFR day type certifciate ii) Not required for day VFR per KOEL iii) Not required per 91.205 iv) Not required per AD Proper steps are to label it inoperative and deactivate it...only I can't deactivate it. So the question is, am I screwed? Since it eventually does come level it seems "ok", but the only reference I can really find about limits is that before IFR flight it should come to level within 5 minutes otherwise it would be considered "unreliable". Not sure if that means it's inoperative though, something that I really don't want to argue with the examiner about. However it's taken 2 months to schedule this so I have a bit of "get there itis" for the checkride. Any guidance?