Answer:
He was nervous
Step-by-step explanation:
He was nervous because Smaug was a dragon and A dragon is very Dangerous and can harm anybody including himself. so he used riddling talk to get him not to know much about him and his true intentions
Bilbo used words like : Bilbo Baggins did not come to steal from you , I merely wanted to gaze upon your magnificence to see if what the old tales talk about you is true. all this words were because he was very nervous and was trying to calm Smaug down