How old is Dalton?  My son Marcus also had high blood pressure in the same range as your son.  It was high until he was about 2 if I remember correctly (he will be 3 in August).  My understanding was that his blood pressure was high because of his florinef dosage (0.2 mg/day).  My doctor tried several times to lower the dose but that caused him to lose too much salt and his 17-OHP and plasma renin would go through the roof.  He was never concerned about the high blood pressure and said that it would cause no long-term problems.  My son was very cranky though, especially when he was less than a year old and I wondered if he was possibly having headaches from the high blood pressure.  Marcus now is on 0.15 mg/day of florinef and his blood pressure has been great the last few doctor visits.  (As babies get older their kidneys function better and they need less florinef.)

Marcus was taken off the salt supplement when he was about 11/2 months old, I think because of the high blood pressure (I was nursing exclusively so this made me kind of nervous).  It may be that your son is getting too much florinef but you have to be careful reducing the dose (at least that was my experience).  I think my doctor felt he was better of with high blood pressure than losing too much salt.  So I wouldn’t worry about it if I were you.  It will probably get better with time.  Do you know what his plasma renin test results have been?  If they are very low then your son may need less florinef.