Is this normal??

Hello! So about 8 months ago or so we had found what seemed to be baby roaches in our microwave. We have long since threw it out and gutted everything and had seen nothing, we also spray once every 2 months with an exterminator. But this week (after the exterminator had sprayed outside) about 3 days or so after we found one full grown roach on the wall near the front door, and then I'm this morning (about 6 days from the spray) I found another one on the oven, in which I checked behind, on the sides, and even inside in which I found nothing again, nothing in any cabinets or drawers beside it. I'm just wondering if this is normal after spraying outside? It's been so long since I've seen anything let alone full grown it's been kinda freaking me out a bit. We have another spray on the inside on Friday, I just don't know if I'm on the brink of a huge infestation or not