Estimates are an aggregation of polls. So you’re going to see a few polls where he’s doing below the average and a few above it. But if there’s a downward trend, you’ll see more lows than highs. 29% is certainly surprising, but if he was already at 38% it’s not wildly out of bounds. If someone showed up with a poll showing him at 47%, I’d assume it was an outlier, but I could easily see how you might land on a group of respondents consistent with this response rate.