Burning Sensation

Well the urethra is very delicate so it's relatively easy for it to become inflamed or infected. Have you had any symptoms outside of this session? If you have perhaps a trip to a sexual health clinic might be in order? I recently had non specific urethritis and had to take antibiotics to clear it up. It's not always sexually transmitted either; it can come on from just being too, ah, enthusiastic in one's masturbation :|. It can also come as a reaction against soap and detergent.

If this was the first symptom though it might just be what the orgasmic energy was doing on that occasion. I get the scratchy/itchy feeling in my urethra as part of my aneros/orgasmic energy 'symptoms'. Sometimes it can be quite intense and almost painful. However my orgasmic energy [for want of a better phrase] is capricious and behaves differently on different days. Unless it was really painful and you've had burning sensations apart from this perhaps you should have another aneros session when you feel ready and just see what happens?

Good luck!