I check my blood pressure regularly (doctor was concerned that it was inching up), however, it is generally close to 120/80. however, recently i received a few "wild" reading such as 140/135 - is that likely an error?

I would consider the lower(diastolic) number as high and you at risk for advancing hypertension. I would invest in a home (wrist) BP monitor and check it several times a day for at least a week. If the numbers are on the high side go in and discuss it with your doc. HBP is a stealth disease often causing organ damage long before the process is treated.