Sorry for your loss, always harder when they are taken too early and we aren't prepared to let them go.
Jolanda and Kaiser
I have a 14 year old female. She's in great health according to my vet so no worries there. But she can be exceedingly whiny at times -- she wants to go potty but its too wet out so she comes and whines; she whines because she wants to go to bed but she wants me to go too; she whines because I'm talking on the phone; she whines because I'm in the kitchen preparing dinner and she wants me in the other room (but she doesn't want to sit in my lap or lay next to me on the couch, she just wants me in the room). She has no problems getting around, up/down stairs, etc. - I take her for walks and and to events (she still likes to sprint race and goes to a senior agility class) but the whining is getting obnoxious.
Perhaps she is telling you that she is near the end? Despite the good report from the Vet and what seems like more than reasonable activity levels for a senior, maybe she just feels a little "off" and wants "Mom" nearby? Or one of her senses (hearing, or vision) is changing? The Vet may not have picked up on it, but she might have...
Of course, I could be totally off base. Just trying to put myself in her paws.
@wizard - I think it is just her age and she may now start having "senior issues"....
@wizard After 14 years, I am surprised you find anything about your Basenji 'obnoxious' ! Surely patience with this old doggie is more than deserved after so many years. She might well be telling you it is her time - my Basenjis have almost always told me - or she might be warning you of the impending time.
If you find her whining obnoxious, could it be that your behaviour towards her has changed ? Are you being abrupt, less affectionate, changed in any way which could be confusing her ?
Time to start analysing your own attitudes, perhaps ?