You never know, unfortunately I think our bodies are a bundle of mysteries.
I've always had irregular periods, so nothing seems odd to me about your cycles, but if it bothers you, going and getting checked out by your Dr will help.
Your average cycle for the last 8 months is 36 days. Most research shows the average menstrual cycle is 23-35 days. You are right next too that. I didn't chart when I was on the pill, but I started in February when I had my tubal and my last five cycles have been 29, 43, 35, 31, and 30, with an average of 33.
Many things can contribute to an irregular cycle i.e. stress, thoughts, emotions, change in your daily routine, thyroid, etc. Try to really evaluate these things for the last 8 months, sometimes even the smallest amout of stress can cause an irregular cycle, depending on the person.
I'm definitely curious as to what your Dr says, so update this thread after your appt.