Sounds like the tech was out sweeping the plant, setting the levels per design out at the pole. if he was on a pole at your house chances are great you have a amp there.
the best thing you can do is call comcast to have them make sure your modem is on the lowest db loss leg of the splitter(in your home) you can. works best to be a straight run off a two way splitter directly off the ground block, starts to get on the fringe after slitting with four way splitters or greater. if you can by pass the four way using a two way (splitter) you might not even have to call them back.