Hey guys I just had my bowstring tightened and the draw weight brought up a bit. But after getting home and about a week of shooting I can fell that there is less draw weight again. What is the reason for this and is there anything I can do to fix it or stop it??

Keep in mind that I am somewhat new to archery, I bought my bow last December, so if this is just common in bows excuse my lack of knowledge.
Hunt & Fish to Live,
Live to Hunt & Fish