Mitchell noted he is "not sure this means anything," but it adds to speculation that has been growing about a potential trade before the August 31 deadline.
Jon Heyman of Fancred reported last week the Blue Jays planned to put him on waivers and trade him once he returns to the lineup.
The third baseman has only played 36 games this season and has been on the disabled list since June 1 with a calf injury. His timetable for a return has also been somewhat of a mystery since being placed on the 60-day DL.
While a team spokesman said earlier this month Donaldson was "ramping up intensity in Florida over the next several days," per Gregor Chisholm of MLB.com, he still hasn't rejoined the major league club.
The 32-year-old has struggled even when healthy this year, batting .234 with five home runs and 16 RBI in his limited playing time.
Still, it makes sense for Toronto to see what it can get in a trade considering he is set to hit free agency and the team is well out of a playoff spot.
On the other hand, a contending team can add a veteran player who is just three years removed from winning the MVP award. He earned MVP votes last season as well while posting a .944 OPS with 33 home runs.
If he can get himself healthy, Donaldson could be a low-risk, high-reward addition for the home stretch of the season.