How long were you gone?
Does your friend just kennel for boarding? Do they get structured time out to play, eliminate, and interact?
6 times in 3 hours sounds like a lot. Is she drinking massive amounts of water or something?
I wouldn't read anything spiteful into it. If I had to guess it either has to do with regressing due to being in a kennel too long and learning to eliminate there, excitement at being home again and a loss in bowel control because of it, stress related due to being away from you for a period of time, or a UTI.
If water intake is way up, she is peeing a lot more, and seems pained or shamed after doing it (tail between legs or sulking away) I would consider exploring if it is a UTI. Again if she was left too long without structured periods to eliminate it could lead to a UTI.
Not talking down your friend or their ability to board, just offering up what would be going through my mind.
~Chris~
_________________
Is this about the cake problem? What's the matter with you mathematicians, cake is never a problem. - Professor Lazlo