Montag runs the risk of being caught and eliminated. He also runs the risk of putting others in danger.
Montag's actions are impetuous and based upon survival. I've always found it odd that he ran straight to Faber. Montag knew he was being followed, and he knew the degree to which the search would turn. He put the older man in great danger in an attempt to secure his own safety. In the end, however, we see that Montag has secured his escape..... reached his destination, and secured a place among others who seek what he seeks. As the city is destroyed, we can't help but to believe he did the right thing and wish him well on the journey that stands before him.