No, no need for that. But...
Up vote great content and correct information that helps directly solve issues on the site. Was there effort? Get that guy some rep! Was it sloppy, confusing and all in all a not so good post? Well, its up to you.
Bad content, wrong information, you don't agree with the posted information or the information is dangerous? Down vote, do nothing, again, its up to you.
The key point is: the more voting, the merrier.
Asking for votes? Well, not the best you can do with your time on the site, accepting an answer and not up voting it is normal and I don't consider it rude. Neither asking for an up vote, is. No need to make a fuzz about it I think.
If you don't agree with it you can flag it as chatty, if the same user keeps asking for for on the same post or any other posts constantly then probably the mods will send him/her a courtesy PM and we all move on with our lives.