I usually get straight up peaches from the bag. I get peaches and grapefruit from my all Amarillo IPA, 85 ibus, with a kind of stinging grapefruit right at the end. What were your bittering hops, I can think of a couple described as dank?
I'm not bittering with Amarillo. IIRC I used Warrior to bitter in all of the beers I'm referring to. It's a pretty clean bittering hop, so it shouldn't be coming from that. I used various combos of hops. One recipe was warrior, amarillo, and cascade. One was warrior, simcoe, citra, and amarillo. I would point the finger at simcoe, but it wasn't used in the first one. Plus I made a citra/simcoe IPA that turned out great. Nice citrusy flavor and aroma.
How clean are your lines? I pick the same flavor you mention in my IPA when my lines need cleaned and for some reason my IPA lines need cleaned more than my other beer lines. I just cleaned them a month ago and had to clean them again two or three days ago on the IPA tap. It's too the point that if I leave my IPA untapped for a couple of days the first pint is foul and goes down the drain.
I clean the hell out of them with BLC (this time I used Liquid Line Cleaner), do a potable water rinse, then a Star San rinse. I usually pull off a pint or two before I drink the first one from a keg. I'll usually replace the lines after 4 or so uses. Maybe I'll replace the line and see what I get. The funny thing is, though, that I was getting the same flavor from the picnic tap, which was also clean. IDK, I'll try it again.