Late periods on the pill!

I've been taking the pill since March of this year. The first few months were great. As soon as I finished the hormone pills I would get my "period" on that Sunday. However the longer I'm on it the longer it takes for the bleeding to start. This month I didn't start until Thursday instead of Sunday. It has gotten to the point where I'm on the hormone pills of my next pack and I'm still bleeding. Should I get my hormone levels checked?