Poloniex looks like a good, old Mintpal.
Pump after pump
The little DASH pump could have been anything.
Could have just been next in line since a lot of alts do seem to be getting pumped, but I think part of the reason for the recent wave of altcoin pumps is the problem with bitcoin struggling to scale. Pumpers may plan to dump asap, but they aren't stupid and do tend to do it when something is looking like it wants to go up anyway. When you've just tried to make a bitcoin transaction and waited ages for it to confirm, instant transactions do gain a new appeal.