Could be. When males go after females to breed; there is a window of fertilty during the females heat cycle(about day 9 out of 21 days) that makes a female receptable and a male will really be. The male will usually be interested right before the heat begins and during this particular period. Not to say they can’t be interested at other times. This is just what I have observed. There has to be a reason for that dog to be interested.
Back when I worked for a vet we did occasional artificial inseminations. To put it delicately, a male dog can certainly be trained fairly easily to go thru the motions with a less than natural partner.
So, I’m assuming the dog could have been trained to do something like that. In which case I would still be a little suspect of the mother, or a family member (whose dog was this?)
susie