Are angina attacks a month after a mild heart attack a common occurence for a male in his mid 40s?

I know a guy who is 44 and had a heart attack (mild one) about a month ago. He was feeling great the first four weeks, but suddenly started having minor bouts of angina the last week or so. Nothing debilitating, just tweaks of heartburn and light-headedness, but would go away with a blast of nitro spay. Is this common? Should it be a major concern, or is it part of the healing process?