Income of what exactly? Bitcoins or USD?
If you're on deepbit I'd say that's almost impossible, there was a period of unluckiness that deepbit hit, where the 24hr average block time was 23 minutes per block, right now it's 15 minutes per block (with 400Ghash/sec less).
Just a rough calculation there would suggest 1Ghash @ 23minutes / block (2300GHash)= 1.36BTC / day
while 1GHash @ 15minutes / block (1900Ghash) = 2.53BTC. Pretty sizable variation.
EDIT: 1Ghash @ 15minutes / block (3300Ghash) = 1.45BTC/day.
Not to mention before the difficulty jump total GHash was about 1900, then it went up to 2400ish, which would drop your payouts even at constant block generation.
If you're meaning USD then yes that could be true. You lose BTC generation but gain BTC value.
EDIT: Holy crap deepbit is 3300GHash/sec, I must be tired and reading wrong.