I would say so. A little jealously is completely natural and healthy I believe, so long as it is within reason. By that I mean, I believe a guy being a little jealous if his girlfriend is going on a road trip to cancun for spring break with 10 guys and will be sharing a bed with one is completely justified/understandable, but not a guy being jealous over his girlfriend merely even speaking to another guy.
As human beings, it's completely natural to worry about the things that mean most to us. For example, if I let my friend borrow my ford p.o.s. that's about to break down on me, chances are I won't be too worried about what might happen to it. However, if I let him borrow my audi, I'm probably going to be really paranoid/worrisome. I'm going to ask him to PLEASE PLEASE be careful and always use his signal lights and so on, get it?
I don't really believe there exists people who never feel even an inkling of jealousy, it's completely counter-intuitive to being human and knowing our limitations (i.e., we're imperfect). It doesn't matter how secure you are in yourself, you should know you're not perfect, and therefore not the most supremely desired human being that is and ever will be.
I highly doubt those who "are secure and comfortable in the relationship and himself/herself" would not have a nerve struck if their partner spent a night having drinks with brad pitt or jennifer aniston or some super model or whatever. In that case, the only logical conclusions I could come to are either 1) that person does not really care (i.e., I am that person's ford p.o.s.) or 2) it's just a facade because face it, society frowns so heavily upon jealousy and people are deathly afraid of appearing needy just by showing they are uncomfortable with a situation 3) The person I am in a relationship is some egomaniac. I think option 2 is the most likely of them all.