Is this seperation anxiety?

I go to school 4 days out of week, I just went back for my spring semester last week. When i get home i usually ask my. MIL how much my son ate & when he last napped so i can get an idea of where he is at in his routine. Since going back whenever i leave him with my MIL or even his dad the 2 days he stayed home, he only drank the milk i had pumped before leaving for school & napped only once. Mind you im gon for a good 6-7 hours at most. Today i came home to find out he hasnt napped since i first left for school which at that point had been 7 hours. He usually naps every 3 hours. Once i get home hes drinking & sleeping again like normal. Could this be a form of seperation anxiety?