1986 Pontiac Fiero 86 Fiero gt overheating

This (86 fiero gt) car is my car now my dad has had it for 7 years and now ill be taking this car to school and because of that dmv requires a smog test again, and my question is next, we took the car to smog place, we got their and the guy said it would be pretty quick about 20 to 25 min at most and it was a pretty warm that day around 90s and we asked the guy if there was a place we could get something to drink for me and my dad, he said yeah about 2 blocks away. It was actually 5 blocks away. We then came back drinking our drinks and all a sudden the guy asked us to come over, he said that the car was overheating and we told him that this was the first time, it had never overheated before. I have to say he looked pretty nervous and strange. We then took the car pist off, especially my dad. My question is could the mechanic, the guy done something to the car while we worn't their making it overheat like maybe manipulating the car's computer or something else?