Almost sounds as though he ate something like sherbert. An orange tongue is a little strange. A grey tongue or blue or very red one, or one that may have pigment spots is more common. It may also just be the light that you were looking at it that gave it that colour. Cannot say for sure. If it is something that disappears in a few hours, it may have been one of the above and as long as he is clinically fine, then no problem and no worries.
If it remains a concern, then have your vet look at it to make sure. The only other thing I can think or suggest is if he is jaundiced, but then there is usually a yellow discolouration of the tongue, gums, cheeks, insider ears and the white around the eyes also are discoloured.
Martin Slome DVM
Centre Street Animal Hospital
7700 Bathurst Street Units 40-42
Tel. (905) 771-9855