With blood pressure, it's generally nothing to panic about. You need to run high pressures for many years to do damage.
Most high blood pressure is Essential Hypertension - so called because it happens for reasons we don't understand.
It does happen a little more commonly on treatment but happens before, during and after treatment so the simple reason.... it happens.
We used to use 160/90 as the treat/no treat limit. It's crept down over the years to (depending on country) to around 145/85 (lower for diabetics)
But the extra benefits for getting diastolic (the small number, and the more important number) below 90 (ish) are small so at best your problem is mild.
Keep an eye on it for a while, and if it stays up an ACE inhibitor or and ARB would be good choices for treating it.
Because we don't know the cause we do observe that some patients can stop their medication after, say, a year and everything is back in whack.