Hmm, yes, this looks kinda weird, I'm not sure what was going on given your hashrate (and hard to be sure without access to the server-side console, I guess the pool operator would have to chime in)

I see similar drops only for miners with low hashrates at my pool, but for them it's expected.
http://fairpool.co.vu:9640/static/graphs.html?Day
but miners in the 40-50 kH/s are already seeing constant income, let alone at your 2 MH/s.

But then my pool is only at 800 kH/s, so there may be some other issues popping up in higher rate pools.