We fostered a Labradoodle (Jett) that had several black spots on his tongue. DH used to joke that it looked like he ate an ink pen! I would ask though if it has always been there? If it is something just just appeared I think I would check with my vet as a precaution.
Our first F1 doodle had a black spot on his tongue. We just laughed at him and affectionately called him a "mixed breed!' Sometimes we even called him a 'mutt!' LOL! Really don't think there's anything to worry about!
Very interesting! I thought that only chow or shar-pei mixes had black/blue on their tongues. (BTW, I am in no way suggesting that Monty has chow in him!!) Our Dixie looked like a shepherd/collie mix (actually looked a lot like a Belgian Tervuran) but she developed black/blue spots on her tongue when she was around 6 months old (can't remember exactly - that was 11 yrs ago). We assumed that she had some chow in her but as we found her in the middle of the road at 8 wks old, it was all a guessing game. Sounds like the spotted tongue can show up in other breeds - good to know :-)