cycle length concern

Tara
I've only been charting my cycle for 3 months now, but I've noticed my cycle length is growing. The first month was 32 days, followed by 36, and am currently at 38 days with no sign of AF coming soon (I took a test on 1/1 that was negative). Is this enough cause for concern to contact my doctor? 
I was on the pill for 2 years before TTC in Oct.