Sunsets and lens flare

[canon shooter]

Took some sunsets and some of them have some lens flare. This is concern to me, as I have spent good money on lenses. I used the 24-105L, which is an expensive lens (at least by my means).

Does lens flare mean the lens is not made well, or something wrong with the lens?

[SilverHCIC]

Post some pics so we can see. There's probably nothing wrong with the lens. ... Moreover, it's probably an issue regarding a singulary bright spot on an otherwise dark background. I have experienced occassional lens flare with a number of lenses, including my L's. Good build & quality optics will not necessaruly eliminate all lens flares!!
... But without seeing one of you images, it's hard for us to provide much insight into your potential problem.;) Post an image and let us see.

[RadAL]

maybe a polarizer would help? But yes, show an example or two to show us what you mean.

[Rock]

Do you have hoods on the lenses in question?