I beleive that this behaviour is male.....as only my male does this....especially when he is caged with one of my females. None of my females have done this...and i beleive only males will do this.... From your picture, however...i note that the head of your mali has not really darkened....one tell tale sign is that the head will begin to darken and eventually turn black...my male is just over 2 years old now and has a black head, arms, and legs....with quite a neon yellow back.... So, if the head of your mali begins to turn black...it's 100% male. but if it's head remains grey/white then it's probably female... you'll notice 2 bulges just behind the femorial pores in males....after about 2-3 years...these bulges become pronounced (when compared to a female) it's more difficult i guess if you only have one uro.... but I hope this helps.... I find my male to be the best tempermented out of all of mine....i'd beinterested to ear what other ppl think about preferences between uro sexes.... nywayz, as long as it's healthy and happy...enjoy! 
~Chris~