There is a chance his teeth may need cleaning or it could be something much worse. Black sposts showing up on gums and the tongue can be a sign of mouth cancer, FIV (feline immunodefficiency virus) can cause raised spots in the mouth, etc. This may be nothing serious or it could be the early symptoms of something that is (and if it is a dental cleaning needing done and it is not, this can lead to serious health issues down the road). Yes, getting cats to the vet especially if they have not been trained to crate and ride well is stressing for all, but ignoring medical treatment when there is a chance it could be something serious is cruel. I drove 500 miles plus in one day with four cats – one of whom was from a feral colony and spent the first two hours hissing, screaming and trying to grab the back of my head. I have a male who pees in the crate pretty regularly out of stress, I just add extra towels and have a plastic bag handy to toss wet ones in. But I still make sure vets runs are done whenever neded. 15 – 20 minutes of stress crated in a car is far better than finding out that a problem gone untreated because of the hassle for the human is now past treatment. And I also have a cat (formally a feral cat as well) that is fine at the vet and once crated, but that initial getting her into the crate for the drive down requires a heavy denim jacket! Yet my other cats willingly enter a crate and ride quite well – but I had the chance to teach and work with them to adapt to riding. What I an trying to say is there should never be an excuse for not seeking medical treatment – even if it means a bit of hassle and some scratches as a ticked off cat. The spots could be nothing, but they could also be the sign of something serious and should be checked out to rule out the potential of that serious problem…