There have been 73 payments, and the average payout from the last 72 is 450.

The average over the past 44 payments is 731.4, The average over the past 22 is 781.86, and the average over the past 15 is 827.   That's consistent with an increasing amount. (I assume it was different for you since you calculated it at a different point in time)

Anyway, we haven't seen any more inexplicable payments come in so far other then the one at 9/23 at 16:17.  It's likely that was built up earnings, but it's not clear who built it up.  Since it was only once it could actually have been from someone outside of labcoin. On the other hand we haven't seen any other manual payments since then.

The automatic payments only pay out exactly your threshold, and leave excess in your account it only sets a floor for the hashrate.  The manual payments are the ones that are "informative" and tell you what the actual hashrate is. If any come in.

If was only one account hashing, then a manual payment would only be for the excess since the last manual payment plus whatever was made since the last auto-payment. If there are multiple accounts (Whether it's labcoin or someone just trying to pump their stock), then the excess could be built up in the second account.

But clearly there were multiple accounts pointed at that address at 16:17.  Whether that was labcoin or someone else is unknown.

If you're only looking at a 2 day average you're obviously not going to see short term movement.