Lets just say my dog has eaten everything under the sun, I mean everything from cat poop, baby formula, dirty diapers, takes food off the table when no one is looking I mean I can go on and on, I surprised she's still alive with all the stuff she has eaten. So I don't think A little bit of pumpkin will hurt her, Heck I'm surprised my dog hasnt eaten our pumpkin we have sitting on our window.
It should be fine but just a warning. Pumpkin can act as a great laxative!
I'm not aware of any problems with pumpkin and dogs, and as long as it was a "little taste" there shouldn't be a problem. How old is your pup? I love Shepherds!