The bleed through on one channel is indicative of the master pot not grounding out completely at stop position. It may get worse with time, but nothing to worry about.
Not a bad idea to replace the tubes, and this will take any question mark out of your mind. Could cause the sharpness you hear also. I would put the Ruby KT88's in them from Doug's tubes. The ones that are AKA Penta Labs. http://www.dougstubes.com/power-tubes/ruby-kt88-v-str.html
For the Rectifier, you can splurge and put NOS Mullard GZ34's in there or get some new Sovtek 5AR4's from Doug's tubes as well. The Mullard is slightly better sounding IMO, and last much longer, but not much gains in performance really for the cost. You can put new Sovtek 5AR4's in there every year or so very cheap. http://www.dougstubes.com/rectifiers/5ar4-gz34/sovtek-5ar4.html
If you want really good front end tubes, go with the Mullard CV4003 in the 12AU7 slot and Mullard standard NOS 12AX7's.
http://www.upscaleaudio.com/12au7-ecc82-cv4003-5814-6189/mullard-cv4003-12au7-vintage-new-old-stock/
https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=0ahUKEwj2kLPn9pvMAhUJ5yYKHW4BBpMQFghXMAA&url=http%3A%2F%2Fwww.audiotubes.com%2F12ax7.htm&usg=AFQjCNEQOc-wWqSO_1Xcx0QAGNcEetvshw&sig2=VFmgZVLyw8M-FElAVe2usQ
On the Brent Jessie site, scroll down till you see the Mullard Matched Pair from the 60's, for $185 per matched pair.