Hey guys, so last year I got a fender reissue blues deluxe and I love it. I play an American standard fender strat and an epiphone pro 335. I have been playing through the amp for the last year with no problems and never heard any fret buzzing. Recently, I have noticed a very high hissing buzz on my epiphone but only on the 9th of the g and on the 14th of the d and on no other strings at those frets or anywhere else on the guitar. I have gone though all the troubleshooting that I can think of to try to get rid of this buzz and I can not seem to get it to go away. I plugged in my Stratocaster which has never had a buzzing problem and the same exact strings at the same exact frets are buzzing. And its not a rattling buzz like I've heard before...  its a very very high pitch hissing sound, almost kind of the sound of the reverb in an amp rattling. I have gotten to the point of not knowing what the heck to do to get the buzz to go away haha and I just cant stand to play because now its all i hear. Im beginning to think that it is not the guitars since I have started from scratch setting them both up and the hiss is still there. Has anyone heard of anything like this? Could this be a problem with the amp that is making this hissing noise? Is it time to replace the tubes? I bought the amp used so I'm not sure how old the tubes are so it very well could be time to replace them. This is my first tube amp so I'm not sure if this is the indication of needing new tubes or not. 

Any help would be greatly appreciated! 
Since it's happening to both guitars on the same frets, the problem may be with the amp.  Have you tried swapping out the preamp tubes?

Also, have you tried your guitars on a different amp just to confirm the issue isn't with the guitars?
It is the amp. Apparently I'm not the only one to have found this problem with this amp. Found multiple videos and things online regarding the fender blues reissue having a high hiss sound. Gonna look into that and see what  I can do but from what I read so far it is something to do with the tubes that come installed like you suggested.. Thanks for the response!
its not the amp.  the seasons have changed, the temperatures have changed and there is more humidity in the air, they most likely need a slight truss rod adjustment.