This is in the mastering forum, so I guess I'll give responses from the point of view of mastering:
1) As someone just said, "there's nothing wrong with a little hiss". The next thing is that the ear itself is the best noise-reduction mechanism there is. Listen to the mix without any processing or noise-reduction and see if the hiss from the guitar is obtrusive or bothersome. If it is, then we'll have to do something about it.
2) If it's not that noticeable, it can become a problem on the album BETWEEN songs, because you notice hiss most when it goes away! So include a sample of the hiss that the mastering engineer can include to run at low level between the tracks. Suddenly it no longer draws attention to itself by coming in and out.
3) If you have decided that you should do something about it, you can send the raw guitar track via FTP (for example) to a mastering studio that's equipped with a better noise reduction system, one that's more transparent. But it's real hard to judge listening to a solo track out of context. We would not necessarily know how much hiss or noise to reduce, and you have to be conservative, because in context you won't notice the hiss from the guitar as much when it's mixed with other instruments.
4) If you do not have superior noise reduction, I DO NOT RECOMMEND DINR. For an isolated track like a guitar it MIGHT be ok, but usually I find that inferior noise reduction systems take more away than they fix. I would recommend that you send stems to the mastering studio. Two tracks of "everything else", and two tracks of guitar, mixed at the level and with the effects it's going to have in the mixdown. The mastering engineer would then apply superior noise reduction to the guitar track alone, in the context of the whole album, just enough, and not to the entire mixdown, which is ideal. A "win-win" situation (just about). Also, be sure to include a 5 to 10 second sample of the guitar hiss at the level of the guitar, not with more or less gain than you applied to the guitar during the mixdown. The easiest way to do that is to run the song for 5-10 seconds before the downbeat, don't cut it. And the mastering studio will use the noise as a fingerprint for the noise-reduction system.
Hope this helps!