Can you please read the ingredients from the label? It will show what is in the blend in terms of annual and perennial turfgrasses. Usually those contractor blends have lots of annual rye grasses. They germinate fast but are very coarse and you will only get one growing season from them. If this is what you have you should step in ASAP and overseed with a better blend of perrennial ryes, bluegrasses and fescues. You can, of course, fill in with annual rye next lawn season but it will never make for a nice lawn.