"If the average workweek stays the same or goes down and the jobs number doesn't meet it, that's where you have to be concerned," he said.
While the addition of jobs may be a good sign for a recovering economy, a shorter workweek might indicate lower stability or quality of those jobs. With the approaching summer, students are on the hunt for seasonal jobs.
Kinahan said he is concerned by the number of temporary jobs, "as opposed to good, solid jobs" created in the U.S. economy.
Other jobs reports from earlier in the week were mixed.
On Thursday, the Labor Department said the number of people seeking unemployment benefits fell 11,000 last week to a seasonally adjusted 346,000. The four-week moving average was 352,500, an increase of 4,500 from the previous week's revised average of 348,000.
Private payroll provider ADP said on Wednesday that companies added 135,000 jobs in May, the second consecutive month of disappointing gains after averages of 200,000 jobs a month from November through February.