Spots on roof after snowing

So I just purchased a house with a new roof put on my house along with soffit vents and a ridge vent. It snowed a little bit last week. I noticed today there were a few spots on my roof that didn't have snow on it. Could this be due to heat loss or something different that is an alarm for concern? I have no bathroom vents on that side of the house and the insulation is blown in cellulose. Just trying to learn and be a responsible homeowner. Thanks.