@lvoss:
Has your body language changed or the "picture" changed when you now ask for the sit before you enter the house? Dogs do not generalize well so when things change like maybe with warm winter clothes on a subtle body signal you were giving is now hidden by the clothes, the dog no longer knows what you are asking. My instructor is really good about cluing us in to the subtle body language cues we inadvertently give our dogs for various commands. When you start to become more aware of them it really is amazing how much information we give our dogs without realizing it, like a subtle lean in or a head tilt. Dogs are way more visual then we are so hand cues and body language tend to be what they rely on more than pure voice.
Hmmm, I don't think so. She's always been really good about it no matter what.
One physical signal that has ALWAYS worked with her was for me to hold up one finger – I think it started because when she was a pup I tended to hold up her treat between my thumb and middle finger, leaving my forefinger kind of pointing up. Then I noticed that she sat when I held up one finger. 
So, I typically do that, but she's not responding effectively to that either.
I'll have to give more thought to what subtle signals I'm giving or failing to give.
But I think that a couple of days of focused training may help a lot too. I've been very lazy about that cuz she was always so good and never "needed" it..... 'til now {but we know that is a people problem, not a Basenji problem :rolleyes:
