My Jaspar (blenheim) has ears that have faded to a soft pale red. At 6 months though Jesse won't even have his adult coat yet. He will lose the coat he currently has and it more than likely will come in deep red as an adult coat. I wouldn't worry about it.
He is also very likely going to be a big boy -- plenty of growing in him yet. I'd guess he will probably top out in the lmid 20s for weight, perhaps a bit higher, perhaps lower. Boys grow more slowly so he will be around his adult weight by age 12 to 18 months, but will likely add a little more weight up til about 2 or so as he fills out. One rough rule of thumb is that boys are about half their adult weight at 16 weeks old. Can anyone remember his weight two months back?
It is normal for the occasional dog from a reputable breeder to go over/under the breed spec -- sometimes they just get extra large or stay a bit small (a lot of breeders feel any cavalier under about 14 pounds really is too small and insubstantial for showing -- I have heard it argued the breed standard should be higher than the 12-13 lbs it is at the bottom for UK and US respectively). Such dogs would always be placed on spay/neuter contracts in pet homes, by reputable breeders, because they should not be bred. A UK breeder who talked to one of the original breed veterans told me that some lines were developed using springer spaniels or cockers (the CKCS is a reconstructed breed, re-developed in the 20s and 30s) so an occasional throwback to springer or cocker size isn't unusual in some lines. I have definitely seen some CKCS the size of small springers!
But in my experience of working in breed rescue as well as seeing the wide range of dogs that come from show breeders into pet homes, the majority of really oversized or undersized cavaliers tend to come not from the reputable breeders, but from backyard breeders (eg non show breeders who breed indiscriminately for the pet market) and mass breeders (puppy mills). This is because they do not breed with any regard for conformation (what the breed should look like) -- hence you get a lot of thin nosed cavaliers, very large or very small cavaliers, barrel chested cavaliers etc.
I am not sure where Jesse came from but if from a reputable show breeder, it would be a good idea to let them know the size he is growing towards as they'd want to keep that in mind for their breeding programme as there must be some large-size genes in those lines, as he is nearly at the top of the breed standard now (18 lbs) and will clearly go a bit over it. He may just be an anomoly in those lines but they will probably appreciate knowing his size.
This doesn't affect how lovable he is, of course! After all he is a pet, not a show or breeding dog.