Yep...it probably is from the groomers.
At my local Petco, (which I do not get me doggies groomed at but I used once) they have a great requirement that you bring your vaccination records and they be current before they will groom your doggie...I think it helps keep the pups from getting sick for the most part!
but I do not like the idea of a new teenage kid working there every 2 months so I refuse to take my doggies there.
I prefer a groomer with lots of experience!!
or Just do it myself...