Please Help Me with Off-Flavor in IPAs/PAs - Lacto?

Hi,
I’m extremely frustrated lately as my last few beers have this consistent off-flavor. I would decribe it as somewhat sour and acidic. It doesn’t materialize for a few weeks after kegging since the beer tastes great early on. This happened with a Pale Ale earlier this year. Kegged early January, took 40 in a BJCP comp in February, and then scored an 18 in a comp in April…described as very Belgian, sour. My latest IPA (kegged 6/25/12) tasted great initially. I bottled a few about a week later and now it’s got this same off flavor - even trying some from the tap, I think it’s turned as well.

I feel like my brewing process is sound. I replaced my autosiphon and other tubing. I threw out all my plastic buckets and I now ferment in glass carboys. I use Starsan in proper concentrations with proper contact time, I don’t rinse, etc. I do AG batches, pay attention to water profile, pH is always good, etc.

The only things I can think of:

  • I store and grind my grain in my garage which is also where I do my racking and bottling from the kegs. Lactobacillus infection risk. However, I don’t brew there and I’m never crushing on the day I’m racking or bottling (usually not even within a few days).

  • Improper sanitation of kegs/bottles. Less likely than above as I PBW soak and thoroughly rinse kegs after use, then dump starsan in and shake for a while, dump starsan and fill. Bottles are used, rinsed, hung on a bottle tree in garage (same place as racking, milling, bottling). If I get bottles from a friend, I soak in OxyFree to remove labels and deposits. Before filling, I dump them all in a big bucket of starsan solution.

Any other possibilities? I’m thinking I have to mill in a different place. Any help would be appreciated.

Maybe its from your CO2 tank line? I’ve had stuff suck back into the line coming from the tank, and I suspect this has caused me problems similar to yours. I don’t think it’d go into the tank itself but maybe as far as the low pressure side of the regulator.