A home reading of 138/94 is mildly higher than normal. At home, under 130/80 is generally considered normal, and 138/94 falls into what's called elevated to stage 1 blood pressure. One reading alone doesn't confirm hypertension, but it's worth tracking rather than ignoring.
Next Steps
Check your BP at the same time each day for a week, seated and rested for 5 minutes first, and note every reading. If most readings stay over 130/80, see a general physician to confirm it and discuss whether you need treatment.
Health Tips
Home electronic monitors like Omron are generally reliable when used correctly, with the cuff at heart level and no talking or moving during the reading.