Yeah, I'm not aware of anything that would cause astringency to increase. It's always better to keep temps consistent and handle them carefully. I'd look at the feedback as jodell suggested. Keep in mind beer judging is supposed to be as objective as possible, but it's still a subjective process. The order in flight can have a big impact as can how good or bad the beer(s) right before yours was. Also, not everyone is an expert judge. At all the comps I've judged at, they try to make sure novice judges are paired up with experienced judges. Long story short, take the feedback with a grain of salt and look for opportunities to improve, but don't take it as doctrine.
Case in point, last year I had a beer I entered in three different comps. The first two were a local comp and NHC, and were within a couple weeks of each other. Local comp had inexperienced judges and the beer was marked way down saying it was loaded with DMS. The style was pre-prohibition lager and it was made with a ton of flaked maize, so there was some corn character...but not DMS. More experienced NHC judges scored it more than 10 points higher and commented that they really enjoyed the clean corn character. The third comp was another local one, about two months later and the entry was judged by a pro-brewer and experienced BJCP judge and it scored the highest out of any beer I've ever entered in a comp and was in the running for BOS...same beer, same batch for all three comps.
